Whilst Redmond stopped selling retail versions of Windows XP long ago, it is now allowing its major PC OEMs to offer XP "downgrade" rights to customers for a further six months.
These downgrade rights allow PCs loaded with Windows Vista to be downgraded to Windows XP if an end-user prefers to run that operating system instead.
Many users, particularly big businesses, are still concerned about Vista bugs and/or are not ready to support Vista on their extensive systems.
Until now, OEMs were supposed to stop providing XP downgrade rights after 31 January 2009, but Microsoft will now allow them to sell such PCs until 31 July 2009.
At this rate, XP users will be able to jump straight to Windows 7, the next version of Windows after Vista, scheduled to make its first appearance in 2010.