Microsoft's previous operating system might stick around just a little bit longer on pre-built PCs. According to ChannelWeb, Microsoft plans to let distributors take delivery of Windows XP licenses as late as May 30, 2009.

In an e-mail to ChannelWeb, a Microsoft spokesperson confirmed the existence of a flexible inventory program that will allow distributors to place their final orders for Windows XP OEM licenses by Jan. 31, 2009, and take delivery against those orders through May 30.

Previously, distributors had planned to purchase as many XP licenses as they could afford before Jan. 31, 2009, and sell them after the deadline. But once that inventory was gone, they'd have no choice but to turn away XP-seeking customers.

Distributors have until Dec. 31 to submit their XP license demand forecasts to Microsoft, and system builders are reportedly being asked to provide their own forecasts to distributors.

It's yet another sign of the market's resistance to Windows Vista, and of the growing realization within the channel that many customers have decided to simply skip Vista and wait for the arrival of Windows 7. Microsoft says that's slated for late 2009 or early 2010, but some reports have suggested it could come as early as mid-2009.