Windows 7 (32 bit vs 64 bit performance)

So yea, I got Windows 7 and installed it on a 2nd partition but I still primarily use XP so I haven't done a lot of 7 yet. So before I make the final switch and swap all my files and get all my apps and what-not I have a quick question on which I find a lot of conflicting info on.

Am I better off with Windows 7 32bit with 4GB of ram or Windows 7 64bit with 8GB of ram?

I've actually found sites that stated a core2 duo with 4gb ram on 32 bit ran faster than a quad core with 8gb ram running 64bit... That seemed a little odd to me.

I assumed it would maybe lag while loading 32bit software but that would get picked up by the 8gb Ram and that anything developed to run on 64bit would run substantially faster. I know XP64 bit didn't take but Vista 64bit did get somewhere so developers are ready for the 64bit market now. But at this moment in time is it really worth going 64bit?

I'm running a dual core 5000+ BE(upgrading to Phenom in the new year) and I just ordered 4GB CAS:5, 5-6-6-18 Corsair XMS2 ram. I was gonna order another 4GB in the new year as well.

So... whats the verdict? 32bit sticking around or has 64bit gotten in the door enough to make the switch worth it?