Microsoft Windows XP is one of the first operating systems sold to home-based consumers in a 64-bit version. A 64-bit operating system makes it possible to address a very large amount of RAM, which can make the computer operate more smoothly when many programs are running. Examine your system information screen to determine whether your Windows XP installation is 32-bit or 64-bit.
Click "Start," then click "Control Panel."
Double-click "System." Alternatively, you can reach this screen by right-clicking on the "My Computer" icon and clicking "Properties."
Examine the information shown under "System." If you are running 32-bit Windows XP, it will say "Microsoft Windows XP Professional." If you are running 64-bit Windows XP, it will say "Microsoft Windows XP Professional x64." Note that there is no 64-bit version of Windows XP Home.