People are jumping at the 64bit editions of Vista just to see 4gb of memory in use more then realizing that software and hardware companies are still behind in things like driver support and 64bit games and apps. The next version will likely see more support since Microsoft plans to dump 32bit entirely from that point on.
When Windows 7 finally comes out in late 2010 if on time I will be likely dual boot one of the 64bit editions at that time with the 32bit edition of Home Premium now on. The next version will simply replace XP here.
i heard about the driver troubles but i been reading elsewhere with ppl with 64 bit and they all say never once had a problem, only minus i come across was a webcam driver
If you are talking about Vista, then they are the same price. If you're talking about XP x64, then I would only get it if you need to buy a new OS, I wouldn't upgrade from XP x86 to XP x64.