Microsoft has extended mainstream support for Windows Server 2008 by 18 months, and again reminded customers that the still-strong Windows XP will retire in April 2014.
Windows watcher Mary Jo Foley, a blogger for ZDNet, first reported the change.
Announced in the company's newest support lifecycle newsletter, the extension was triggered by standard practices at the Redmond, Wash. developer.
"The Microsoft policy provides a minimum of five years of Mainstream Support or two years of Mainstream Support after the successor product ships, whichever is longer," the newsletter stated [emphasis in original].
In mainstream support, which runs the first five years of a product's lifetime, Microsoft ships free security patches, general fixes and even feature updates. The back-half of the 10-year-support, called extended support, commits the company to free security updates only, although it will provide non-security bug fixes for a price.
But as Microsoft noted, an exception in the rules requires an extension if the follow-up product is slow to arrive.
Microsoft considers Windows Server 2012 the true successor to Server 2008, even though Windows Server 2008 R2 followed the latter in 2009. Server 2012 debuted earlier this month.
The old date for shifting from mainstream to extended support -- July 9, 2013 -- has been bumped to Jan. 13, 2015. And the end of extended support -- in other words, the final retirement date -- has been pushed out 18 months, too: It is now Jan. 14, 2020.
Microsoft's newsletter also reiterated frequently-voiced advice from the company: Get off Windows XP.
"We recommend that customers running computers with Windows XP take action and update or upgrade their PCs before the end-of-support date," read the newsletter, referring to the April 8, 2014 drop-dead date. "If Windows XP is still being run in your environment and you feel that migration will not be complete by April 8, 2014, or you haven't begun migration yet, Microsoft is eager to help."
Notably, Microsoft listed links to several online resources for migrating Windows XP to Windows 7, not to Windows 8, perhaps recognizing that customers are much more likely to pick Windows 7 in any case.
Support extensions are rare, but not unprecedented.
Last February, for example, Microsoft quietly prolonged support for the consumer versions of Windows 7 and Windows Vista by five years to sync them with the lifespan of enterprise editions.
That move was, in fact, more significant than Monday's, as it accompanied a promise by Microsoft to support all versions of an operating system, including consumer-targeting SKUs, or "stock-keeping units," for at least 10 years.
And in Jan. 2007, Microsoft extended mainstream support for Windows XP Home to 2009 and its retirement date to April 2014, primarily to sync its timetable with Windows XP Professional's but also recognizing reality: XP would remain a powerhouse for the foreseeable future.
According to metrics company Net Applications, Windows XP accounted for 42.5% of all operating systems used to reach the Internet last month. At its current -- and relatively slow -- rate of decline, Windows XP should still be powering one in four personal computers in April 2014.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, send e-mail to email@example.com or subscribe to Gregg's RSS feed .