The event was the Linux World Conference in San Jose, a gathering of thousands of computer geeks abuzz with an almost conspiratorial energy. Surrounded by an army of insurgents, the feeling was akin to having stepped into the mythical Sherwood Forest. Thousands of devotees of the new operating system, many of them wearing ponytails and garbed in cowboy hats, leather vests, and red top-hats that screamed "LINUX," flocked to California from all over the world to pay homage to the system's Finnish creator, Linus Torvalds. This youthful Robin Hood of the software world, who shuns wealth, power, and the limelight, is more at home downloading improvements to his system via the Internet from the hordes of eager Linux programmers than addressing a crowd of thousands at the San Jose Convention Center. In an impressive show of technological democracy, hundreds of hands went up when the audience was asked how many had participated in improving Linux by submitting software code, documentation, and code patches via the Internet. But when the same group was asked how many had contributed to the latest version of Microsoft Corp.'s Windows, only one hand went up, much to the delight of the exultant crowd. "That's what's different about Linux," says Larry M. Augustin, CEO and president at VA Linux Systems Inc., Sunnyvale, Calif. "It's not controlled by any one company." There's no question that Linux is where it's at in computing today. Suddenly it's the hip new alternative, the free antidote to what Linux backers consider to be software's feudal ruling class, led by Bill Gates. Unlike Linux, Microsoft's Windows operating systems are proprietary, that is, not open to anyone outside Microsoft and certainly not free. Many leading high-tech firms, including some giant software and computer hardware manufacturers, are offering their products in Linux versions to capitalize on the upstart operating system's expanding popularity. Among them are SAP AG, Computer Associates International Inc. (CA), IBM Corp., Sun Microsystems Inc., Hewlett-Packard Co., Dell Computer Corp., and Oracle Corp. Dell, for example, is pre-installing Linux on its servers. Last month IBM announced a companywide initiative to develop, use, and market Linux Systems for its midrange computers. SAP has already sold a Linux edition of the popular R/3 enterprise system to more than 100 companies. Still, to some business executives the idea of running their company's computers with software that didn't cost a dime, has a penguin for a mascot, and whose creator funded its development with checks from total strangers sounds far-fetched. But many companies are choosing to look the other way and do just that -- use Linux, that is. A free "open-source" operating system, Linux currently is used to run midrange computers called servers, but the Linux wave is sweeping the computer industry, and it won't be long before it's used on desktop personal computers, laptops, and handheld Internet devices. In 1999 Linux represented 25% of the 5.4 million copies of server operating systems that companies purchased, and its share of the market rose 56% vs no gain for Windows NT and declines for Novell Corp.'s Netware and UNIX. And that's only for versions of Linux "for which someone paid something," observes Dan Kusnetzky, program director for operating environments at International Data Corp. (IDC), a Framingham, Mass., information-technology research firm. That figure doesn't count the times companies downloaded Linux for free or replicated it at no cost within their organizations. "Microsoft will have their attorneys at your door if you replicate Windows NT more than once," Kusnetzky adds. About 70% of all Linux software is downloaded from the Web, estimates GartnerGroup Inc., Stamford, Conn. To say that Linux is a maverick OS, the alternative to, say, Microsoft's Windows NT, is putting it mildly. One is free, the other costs companies tens of thousands of dollars. Even then, Windows NT never has been able to shake a reputation as being less than "industrial strength." A business-ready or "commercial" version of Linux, such as that offered by Linux vendor Red Hat Software Inc., costs just $149. By contrast, even the most economical versions of UNIX, a server operating system widely used in the corporate world, costs about $5,000 for a 50-user license, according to IDC . Nor is Linux' popularity confined to wild-eyed, long-haired software developers. It's starting to take up residence at corporations large and small throughout the world. Although it can be downloaded over the Internet at no cost, companies that want to use the new operating system still must invest in hardware, consulting services, and other technical know-how to make it work in their organizations. "Linux hasn't quite reached the mainstream, but it's getting there very rapidly," Kusnetzky says. Most companies that have used Linux say its overall cost of installation runs at about one-fifth that of a comparable Microsoft Windows NT setup. And many companies are moving to Linux because users claim it tends to incur less downtime than a comparable Windows system. One industrial firm that is putting Linux to work is Indiana Precision Technology Inc. (IPT), a Greenfield, Ind., manufacturer of auto parts including air- and fuel-management systems, fuel injectors, intake manifolds, antilock-braking systems, and airbag-control systems. "I was curious about Linux, but I didn't see the business connection," says Bob Moore, IS manager at IPT. "But when I heard that Oracle would support Linux, I thought it might be useful." He tried it out at home. "I began to play with it, and soon my real work got done by Linux." Next, he brought it to work and installed it on a company PC. "It worked a lot better than Windows NT did -- we had no more crashes," Moore says. The next step was a pilot project to try out Linux as a platform for one of the company's systems. IPT chose to test it on the company's intranet database server. The company ran all its internal Web applications on that server with the Oracle database on a Red Hat version of Linux. After 10 months of operation, Moore says, "It never crashed. It never rebooted. The system was rock solid." Moore says the focus of the test was on stability of the system. "That was definitely more important to us than performance," he says. "When you're running a manufacturing process, you don't want to slow down or stop, because if you do, you lose a lot of money." Next, IPT moved its production system, which tracks the flow of parts and monitors the production process, to Linux and Oracle. The system is definitely mission-critical, managing the flow of parts on seven production lines and handling 50,000 transactions daily over three shifts, 24/7. The company evaluated three alternatives: a proprietary system it would have to create, Windows NT, and Linux. "We picked Linux for its stability and cost -- about one fifth that of the nearest alternative," Moore adds. "We're really happy with our Linux database." He says companies considering moving to Linux should be sure to get support from a professional firm that knows the OS. "It's important you have maintenance through [a company such as] Red Hat or Oracle." Other major Linux service providers include VA Linux Systems, Pacific Hi-Tech Inc., SuSE AG, TurboLinux, and Caldera Systems Inc. Another firm that switched to Linux is MicroDisplay Corp., a manufacturer of miniature information displays for portable consumer electronics and projection devices. The company is using a Linux-based server to support its intranet, as well as increased traffic on its Web pages. "Over time, we found that the maintenance and expense required for a Windows NT server was far too great for a small, growing company," explains Bruce Ferrell, systems administrator at MicroDisplay in San Pablo, Calif. "After repeated failures, the NT server was replaced by Linux." MicroDisplay uses the Red Hat edition of Linux to handle a variety of applications, including engineering, file/print service, databases, and Web servers. Ctitek Inc., a Chesterfield, Mo., integrator of computer telephony systems, reports that a client firm replaced Windows NT with Linux after numerous problems with the former system. "A Microsoft FrontPage error on an e-mail form was the last straw that caused this conversion to Linux," says Tony Zafiropoulos, Ctitek president. "After spending countless hours trying to solve the problem, including several calls to Microsoft, we realized that the Windows NT operating system would have to be rebuilt with the latest version." Linux has quickly developed a high-powered following. In November a host of software companies announced plans to create new software applications for Linux, including Corel Corp., Ottawa, Ont., and Provo, Utah-based Novell. They joined a long list of companies that had already supported Linux, such as Oracle. "We've created a strategic business unit focused on Linux," says Ray Wong, vice president for platform technology at Oracle Corp., headquartered in Redwood Shores, Calif. "All of Oracle's products will become available on Linux." Similarly, SAP, the leading enterprise-applications-software company, threw its hat in the Linux ring as a result of customer demand and began offering a Linux edition of R/3 last fall. "We have received a significant number of serious customer requests for R/3 on Linux over the past year," cochairman and CEO Hasso Plattner says. "After extensive testing in-house and discussions with our partners and customers, we are confident that Linux meets our standards." One high-tech firm that is betting big on the success of Linux is Computer Associates. "We see a growing interest in Linux, from both our customers and our partners," says Ken Farber, senior vice president for partner alliances at the Islandia, N.Y., software giant. He says CA plans to distribute 4 million copies of its Unicenter TNG for Linux network management product during the next year. "People can manage the entire enterprise from a Linux box, using Unicenter TNG for Linux," adds Yogesh Gupta, senior vice president for product strategy at CA. "We see Linux going forward having a tremendous opportunity." CA's products run on Microsoft's Windows NT as well, but Gupta sees no conflict as a result. "We absolutely have not had any flak from Microsoft, and we don't expect to get any," he says. CA also plans to offer its Ingres database on Linux. Linux depends on systems integrators and other service firms that can help companies get Linux up and running, as well as give the OS some much needed mission-critical add-ons. One such firm is Mission Critical Linux LLC, based in Lowell, Mass. "Given the amount of time Linux has been around -- commercially available only three years or so -- it is a very mature product," says Moiz Kohari, Mission Critical founder, president, and CEO. "But certain tools are missing to support mission-critical systems." Firms such as Kohari's are needed if Linux is to fulfill its promise as an all-purpose computer standard for various platforms -- large systems, midrange servers, desktop PCs, laptops, and Internet devices. Mission Critical designs systems that monitor, detect, and diagnose problems with Linux. "We're selling our engineering expertise coupled with these tools," says Kohari. His firm initially was made up of 10 former Compaq Computer Corp. employees who worked on development of a UNIX-based server there. Those who are closest to Linux say its real benefits lie in the fact that the OS is what is called open-source, meaning that the basic code that runs the system can be downloaded by anyone over the Internet. "This isn't about delivering just another OS," says Paul McNamara, Red Hat enterprise-business-unit leader. "The fundamental benefits of Linux derive from having an open-source code." Publicly, at least, Microsoft executives downplay the Linux threat, just as they did Sun Microsystems Inc.'s popular Java programming language for the Internet. "We are not seeing that many people move over to Linux," Bill Gates told a packed audience at last year's Workstation Leadership Forum in Burlingame, Calif. And Microsoft's Wintel partner Intel Corp. also tends to play down the Linux effect on the market. "The demand is really for Windows NT, although we support Linux as well," Intel CEO Craig Barrett said. (Six weeks later Intel Chairman Andrew S. Grove appeared as a guest speaker at Linux World.) Privately, Microsoft has been working hard and fast to find ways to poke holes in the fast-rising Linux balloon. Microsoft formed a team of engineers and marketers to keep an eye on the upstart OS and deflate claims that Linux is a far more stable system than Windows NT. At one point Microsoft put a comparison page on its Web site, delineating the benefits of Windows and the drawbacks of Linux. But Microsoft's competitors have already caught sight of a blood trail and are moving to take advantage of it. Companies such as Corel are pushing to help Linux succeed on the desktop. The Canadian software firm, which owns WordPerfect, the still-popular word-processing program, began offering a Linux version of WordPerfect 7 three years ago. More recently, Corel began marketing Linux editions of its WordPerfect Office 2000 suite of software applications and CorelDraw.