Windows XP, originally scheduled to be taken off the market a year after Vista's release, will be available through retail and OEM channels for an additional five months, to June 30, 2008. Microsoft says the change reflects continuing demand for the product and requests for more time to make the transition to Vista.

In the past, previous versions of the OS have been available for up to two years after the release of a successor, but because of the five years between the release of Windows XP and Vista, Microsoft says it expected to be able to shorten that period.

However, the response to Vista has been lukewarm among business customers, many of whom are remaining on XP Professional as their standard for now. For example, according to market researcher Context, Windows XP Professional was on 27% of new PCs delivered through European distributors in Aug. 2007, while its business-focused successor, Vista Business, shipped on only 13%. (Consumer editions of Vista and XP accounted for most other sales.)

Microsoft will also continue to offer the Windows XP Starter Edition, a reduced-functionality version of XP, in emerging markets. The company had announced a Vista version of the product, but much of the hardware sold in price-sensitive emerging markets cannot run Vista well or at all.