The machine won't use it, but there's nothing wrong with a little future proofing while RAM prices are so low.
32 bit is fine for everything. But if you are talking Vista, I don't know (or care) which you should get. I'm avoiding vista for awhile so I don't know much about it.
I am considering vista but also do they not have a 64 bit XP pro? , I know if you go 64 bit you loose the ability to get a lot of the internet freebe software like AVG and stuff
major you need vista.i see no since in building a gaming pc now that is not dx10 capable.