Best way tio test performance W7 32-64 bit

Best way to test it would be to use real world applications. Get FRAPS record some FPS, time video encoding, etc.
Synthetic benchmarks don't give you a true analysis.

I got 3DMark06 to work on mine just fine running 64 bit Windows 7. (EDIT: Ha! nevermind it definitely does not work...I swear I had it running before...)

3DMark06 runs for me just peachy. You may have to install it in another directory besides the Program Files (x86) folder as there seems to be certain restrictions on that folder. Also, run it in XP compatibility mode, or run the automatic compatibility checker that comes with Win 7, which has fixed a lot of problems for me.