How to find Windows XP edition is 32 bit or 64 bit?

Run Msinfo32.exe.
You will get Help and Support Center screen.
Here under "Pick a task" click "Use Tools to view your computer information and diagnose problems "
You would get tools screen.
Here click "My Computer Information" and "View general system information about this computer "
My Computer Information - General , Processor, Version if it says x86 Family it is 32-bit edition
My Computer Information - General , Processor, Version if it says x64-based PC it is 64-bit edition