By Douglas Bartholomew If some CFOs may lack an appreciation of the business impact of IT, that's not necessarily true of their colleagues in the chief executive office. According to a survey of 400 CEOs at some of the world's largest corporations, improving relationships with customers is information technology's biggest contribution to competitive advantage. CEOs also believe that IT has a significant impact on improving supply-chain management. The survey, conducted by the London School of Business, was commissioned by Compass, a management consulting firm. "CEOs are becoming increasingly articulate about their expectations of how IT can contribute to business results," says Rod Hall, a consulting manager at Compass, based in Reston, Va. "They're focusing on specific e-commerce models and on the use of IT to address strategic issues such as customer relationship management, improving the supply chain, and innovation through knowledge management." When asked to rank the top three business impacts of e-commerce, 30% or more of CEOs responding listed access to new customers, improved supply-chain efficiency, more business from existing customers, retaining customers, and better management of information and knowledge. Not surprisingly, most CEOs believe business-to-business e-commerce is having a greater impact than business-to-consumer. For instance, four out of five manufacturing CEOs view B2B as more significant. The opposite is true, though, among CEOs of media and financial services firms, where 53% and 60%, respectively, consider B2C more significant.