Only buy 32bit if you have something you know doesn't work - which is next to nothing these days. The Microsoft fingerprint reader is the only reason I have 32bit (its a silly reason I know. They don't even seem to have it on their website any more)
64-bit! Just check that you have your printer drivers and other device driver for 64-bit OS. You cannot install 32-bit drivers in 64-bit. In my case there is no 64-bit drivers for my printer, and never will be, despite the "coming soon" comment on HP site dated since mid-2007 for Vista, so I had to use compatible drivers from another printer model. Works just as good. The only thing I lost is the ability to mark "Draft" watermark on a paper... (so useless, and if I ever needed it, I'll just add a picture in my Word document)
What about all that problems people had a year ago when it was out? I remember when many people complained about 64bit to be very unstable with drivers.. is it over now?
I have just built a new system and installed 64 bit Home Premium Vista. Can honestly say it is the easiest , most user friendly sytem to install and so so much better than any of its pre-decessors to use. In a word 'get it' dont believe the hype!!