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.