If you don't know which version you've got, then you've got the 32-bit
version. The 64-bit version only runs on 64-bit processors, which are
not all that common as of yet.
FYI - You posted an XP question to a Windows 2000 news group, and this
news group is for Windows 2000 security related questions, so you're off
twice here. When posting questions to news groups, you really need to
spend some time making sure that you're posting to the correct group.