Windows XP was originally due to disappear from store shelves early in 2008 with the purpose of making way for Vista. However, caving into pressure from customers and computer makers, the software giant decided to extend its selling period until the end of June. The new deadline came and went, but while the venerable operating system is now officially off sale in retail, system builder partners were still allowed to sell PCs with Windows XP pre-installed until January next year.

Now, in yet another sign of the market's resistance to Windows Vista, Microsoft is giving system builders a way to obtain XP licenses through distribution well after that deadline, by letting them submit their demand forecasts this month and take delivery against those estimates through May 30, 2009. The new scheme will allow distributors continue selling XP-based systems without having to hand over cash for the new licenses until they have already sold them – rather than having to stockpile licenses before the cut-off and hoping to sell them afterwards.

The extension effectively results in Windows XP continuing to sell through nearly all of Windows Vista’s active lifetime and suggests that shortly after May is when we will see Windows 7 debut.