Microsoft support for the Windows XP with Service Pack 2 (SP2) operating system will end July 13, 2010, and support for the Windows Vista Release to Manufacturing (RTM) operating system will end April 13, 2010.
Note: If you are running the 64-bit edition of Windows XP with SP2, you’ll continue to be eligible to receive Microsoft support and updates until April 8, 2014. There is no SP3 for the 64-bit version of Windows XP.
To find out if you are running the 64-bit version of Windows XP, go to the Start menu, right-click My Computer, and then click Properties. If you don’t see "64-bit" listed, then you’re running the 32-bit version and need to install the Windows XP SP3 for it to be supported by Microsoft.