By John S. McClenahen In contrast to this month's sharp drop in the Conference Board's index of consumer confidence, the UBS Warburg Index of Investor Confidence is headed upward. It rose six points in August from its all-time low in July. True, investors surveyed by the Gallup Organization for UBS Warburg LLC now expect their portfolios to show a lower rate of return during the next 12 months than they did earlier this year -- a 7.4% rate of return currently projected versus the first half of 2002's expectations for a 10.5% return. However, 54% of those surveyed this month contend it's a good time to invest in the stock market, up from 50% in July. And 63% of investors, up from 56% in July, now believe the stock market will be higher in a year.