The next wave of growth will come from the Internet.

Microsoft will spend $3 billion on research and development this year to keep improving its products, said its chief financial officer, Greg Maffei. "If you let Windows stay stale for even three or four years, it will be a dead product," said Maffei, who spoke last night at Harvard Business School_s entrepreneurs_ conference and awards ceremony in New York. Microsoft increased its sales quickly as it rode the PC revolution that began in the late 1970s. The next wave of growth will come from the Internet, and Microsoft is investing to make sure it rides that wave, said Maffei. Microsoft has been struggling with its Internet strategy with products such as its Microsoft Network online service and its content and electronic-commerce Web sites, which together have been losing money. Other rivals such as America Online have had more success at gaining both subscribers and profits.