Responding to some customers' lukewarm embrace of Windows Vista, Microsoft (NSDQ: MSFT) said it will extend by several months availability of the operating system's predecessor, Windows XP. The company said it will make the full version of Windows XP available to PC manufacturers and retailers through June 30, 2008. It will continue to offer a basic edition in emerging markets through June 2010. Microsoft introduced Windows XP in late 2001. The company ordinarily makes operating systems available only for four years after launch date. But delays in producing Windows Vista, which debuted in January, forced Microsoft to continue selling Windows XP longer than planned. In recent months, Microsoft had pegged Windows XP's official expiration date at Jan. 30. That will fall by the wayside in favor of the new dates, Microsoft said Thursday. Microsoft's official explanation for the move is that too many customers have yet to complete the transition from Windows XP to Windows Vista. "There are some customers who need a little more time to make the switch," said Mike Nash, Microsoft's Windows product manager, in a statement posted on the company's Web site. While that may be, a number of signs have emerged in recent months that Windows Vista's problems go beyond timing. A survey conducted earlier this year by InformationWeek showed that an astonishing 30% of businesses have no plans to purchase Windows Vista. It's an indication that many corporate software buyers may take a long look at Linux, the Mac OS, or some other alternative to Vista once Windows XP is no longer available. Among other things, software buyers have railed against Windows Vista's price, lack of compatibility with existing software, and system requirements that exceed the capabilities of PCs more than a couple of years old. PC makers have responded to such concerns by continuing to push Windows XP, despite the millions of dollars that their partner in Redmond has spent promoting Vista. Dell (Dell), Lenovo, and Hewlett-Packard (NYSE: HP) have in recent weeks gone as far as offering customers discs that effectively let them "downgrade" their Windows Vista systems to Windows XP. Despite such troubling signals from the market, Nash insists that Microsoft doesn't believe Windows Vista is destined to become the tech industry's version of the Ford Edsel. "Windows Vista is on track to be the fastest-selling operating system in Microsoft's history," Nash said. Nash, on the Microsoft Web site, noted that Charter Communications and Continental Airlines are among the companies that have moved to Windows Vista "incredibly fast." Microsoft said it has sold more than 60 million Windows Vista licenses to date.