For years, software makers invented operating systems and applications that required more computing power, leading to a demand for new chips and other hardware--a cycle that has been likened to the automobile industry's infamous practice of "planned obsolescence." The release of Windows XP, however, may mark the formal end to that cycle as consumers and businesses find increasingly that the equipment they already own is good enough to run most of the software they need. With the U.S. personal-computer market largely saturated, Microsoft must depend on sales of Windows XP to customers upgrading from older Windows versions, instead of to those buying new PCs. Businesses running Windows 2000 will find their existing systems adequate to run XP. Consumers with a minimum 600MHz Pentium III-based computer also should find their hardware adequate for running Windows XP, though older systems could require extensive upgrades or replacement. "There isn't a motivation to go get the latest, greatest thing as there was back with Windows 95," IDC analyst Roger Kay said.