In an unprecedented move, Microsoft has committed to providing support services for its soon to be retired Windows XP through 2014 -- a full 13 years after the operating system was originally released.

In a letter sent to customers this week, Microsoft senior VP Bill Veghte said the software maker will provide security patches "and other critical updates" for Windows XP until April, 2014.

"Our ongoing support for Windows XP is the result of our recognition that people keep their Windows-based PCs for many years," Veghte wrote.

That may be, but Microsoft normally terminates support for an OS within ten years of its release -- at the latest. For instance, it plans to end support for Windows 2000 in 2010.

Microsoft may have little choice but to support Windows XP for an extended period, given that the majority of its large business customers have not upgraded their personal computers and laptops to the newer, Windows Vista operating system.

Many companies have balked at Vista's cost, resource requirements, and lack of compatibility with older applications.

Microsoft released Vista in January of last year. But the company has apparently accepted the fact that many of its largest customers will skip Vista altogether and will continue using XP at least until Windows 7 becomes available three years from now, and possibly longer.

In addition to supporting XP through 2014, Microsoft is now actively promoting a program that allows customers to downgrade Vista systems to XP through a loophole in the company's licensing terms. Microsoft's software license allows customers who purchase a copy of Windows to install and run a previous version of the OS at no additional cost.

"It's true that we will stop selling Windows XP as a retail packaged product and stop licensing it directly to major PC manufacturers [after June 30]," wrote Veghte. "But customers who still need Windows XP will be able to get it," he said.

Beyond the downgrade program, Microsoft will continue to make Windows XP available to manufacturers of low-cost PCs incapable of running Vista through June 2010. Low cost PCs, like the Asus Eee PC, are gaining popularity in fast growing emerging markets like India and China.

Without continued access XP, manufacturers of such systems would be forced to offer them with the rival Linux OS on board -- a situation Microsoft is hoping to preempt.