^Yes. Win 7 x64 uses a bit more RAM than x32 does.
But don't bother with 32-bit. More and more programs are being developed with 64-bit in mind. In the professional media level already there are programs that only exist for 64-bit (After Effects, Premiere) and eventually that list will get bigger and bigger while the list of 32-bit applications shrink.
If you like to game be sure and have 4GB of RAM; that's pretty much the magic number for most cases.