Hello Mike,
Whether you'll get a better gaming experience with 64 bit is dependant on if the game has a 64 bit exe and some do. You can also benefit from the increased max ram limit of the 64 bit version. I've been playing all of my games on 64 version with no problems what so ever. Some of the game do seem to run better on the 64 bit but I have no real hard data to back this up. I have a large game collection that plays fine on 64 bit Vista and Windows 7 64 bit including Demon Stone which is very old (Win 2000/XP) all without having to use compatability mode. So you should be fine with the 64 bit since video card manufacturers offer very good 64 bit drivers.
I hold to a simple philosophy: just assume everyone's a piece of ____ and then be pleasantly surprised if you find anyone who ain't.