I just built a new computer, and I am asking myself that same question: XP 32bit or 64bit. I have 4 gigs of memory, which will only be truly utilized in a 64 bit OS. I have seen a lot of complaints about software compatibility. However, most of those reviews are quite old. Has XP 64 bit gotten better? I know that all my hardware is supported in XP 64, so the only question is software compatibility. What do you guys think?