Forget the 64 bit stuff. Despite IT geeks salivating and writing up articles that reek of superlatives, about 64 bit chips, the reality is that virtually nothing you want to use is compatible with 64 bit.
I rebuilt the wifes computer a couple of years ago, and took the breathless advice of geeks, and installed a 64 bit chip, and installed 64 bit Vista - and it's the worst thing I've ever done. Virtually nothing that we try to plug in to it, will work - and the "incompatible program" message is prompt and frequent.
Select 32 bit, it will do all you want in a highly satisfactory manner, and you'll have no compatibility problems whatsoever, with current programs you are using. I don't have any experience of W7 with 64 bit, but as it's based on Vista, I don't see where they could have done anything substantial about improving compatibility. I'm running W7 on my laptop, and it's 32 bit, and it works very well.