Support for Windows XP with service pack 2 and Vista will be discontinued after July 13 this year. See the complete article at:
http://oem.microsoft.com/downloads/ADD54268-AC45-4158-A87E-6C8166D1123E/worldwide/windowsxp/windowsxp_sp2_windowsvista_rtm_eos.pdf

Be sure to take a look at this important deadline that is coming up in a few months.