Microsoft dropped support for Windows Vista Service Pack 1 this week, and recommended that Vista users buy Windows 7 or upgrade to the most recent version of Vista.
There were two Vista service packs. Support for the first ended Tuesday, while Service Pack 2 will continue to receive mainstream support until April 10, 2012, and the more limited "extended support" until April 11, 2017. Once support for a service pack ends, that software no longer receives security updates.
In the Windows Team Blog, Microsoft said: "We recommend folks look at upgrading to Windows 7, which is the fastest selling operating system in history, selling over 400 million licences to date. Windows Vista users can also use Windows Update to update their PC to the latest service pack available which is Service Pack 2."
The end-of-support dates follow published Microsoft policies, and so are known months or even years in advance.
Just because your software is out of date doesn't mean you need to buy a new computer. A Vista machine can upgrade to the second Service Pack for free. Many Vista machines have the hardware necessary to upgrade to Windows 7, and this week Microsoft said any PC capable of running Windows 7 will be capable of future upgrade to Windows 8.
Since Vista was never that popular, the bigger issue applies to users of Windows XP, still the most widely used version of Windows. All support of Windows XP Service Pack 2 ended last year, but XP's third service pack is on extended support until April 8, 2014. According to Microsoft, sales of PCs with XP pre-installed ended last year and sales of PCs with Vista pre-installed will end in October of this year.
Microsoft is starting to show previews of Windows 8, signalling that it could come out sometime next year. How long Windows 7 continues to receive support has not yet been determined.