Microsoft just can't quit you, Windows XP.

The final shipment date of Microsoft's aged, yet distinctively non-Vista operating system has been extended yet again (http://news.bbc.co.uk/2/hi/technology/7795302.stm). System builders can now obtain Windows XP until May 30, 2009.

Windows XP was originally scheduled for OEM extinction on January 31, 2009. That deadline was given once (http://www.microsoft.com/presspass/features/2007/sep07/09-27xpsalescycle.mspx), twice (http://www.theregister.co.uk/2008/04/03/microsoft_extends_xp_shelf_date_for_ulcpcs/), three times (http://www.theregister.co.uk/2008/06/03/windows_xp_license_extension_take_two/) the delay to mid-2010, provided the Windows XP licenses were for netbooks and low-cost PCs that can't handle Windows Vista - or perhaps more importantly, can and do support Linux.

Microsoft has a problem, though, given the popular opinion of Windows Vista ranks just below Typhoid Mary in terms of "must-have" status. PC makers selling larger systems have been working around the January 2009 Windows XP expiration date by offering Windows-Vista-loaded machines with an option to downgrade (http://www.channelregister.co.uk/2008/06/24/xp_vista_windows_roadmap/) to Windows XP.

Under the new, four-month extension, PC makers must still purchase licenses before January 31, but can choose to have the licenses delivered through May 30, 2009. This is apparently a move to keep system builders from stockpiling licenses as currency in a post-XPalypic future or at least until Microsoft can shove early versions of Windows 7 out the door in late 2009.

The latest extension means Windows XP is now coming in just short of being Microsoft's longest-offered operating system (http://www.microsoft.com/windows/lifecycle/default.mspx), with 89 months of desktop license availability. The winner by a nose is MS-DOS 6, which was available to system builders for 90 months. ®

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