64 or 32 bit windows 7

with 4gb macbook pro (allocating the min 2 gb of ram)

which, from experience, would run faster, 32bit windows 7, or 64bit?

as a student, i can buy either one for $25 in the college store, but im not sure which to get, only use windows for a few apps (office 7 etc), so speed is the most important.

i havent bought parallels 5 yet (I have 4), but if it will run faster under it, i will.