Windows XP SP2, will no longer receive updates after July 13, 2010. This does not include 64-bit Windows XP SP2, since there has been no SP3 release for the 64-bit OS. The 64-bit version will be supported until April 8, 2014. A fresh install of Windows Vista, with no service pack installed, will no longer receive updates after April 13, 2010. Microsoft has decided to drop support for these versions of Windows. Users of XP SP2 will need to install the free upgrade to SP3 and Vista users will need to upgrade to SP2.

Read the information page from Microsoft to learn more and to see all of the options available.