Follow the following steps in order to find wheteher your Windows xp is 32-bit or 64-bit .
1.Click Start, and then click Run.
2.Type winmsd.exe, and then click OK.
When System Summary is selected in the navigation pane, locate Processor under Item in the details pane.
Note the value.
A. If the value that corresponds to Processor starts with x86, the computer is running a 32-bit version of Windows.
B. If the value that corresponds to Processor starts with ia64 or AMD64, the computer is running a 64-bit version of Windows.