I would go with RealTemp or CoreTemp than. The one advantage to RealTemp is you can calibrate your sensors to get a more accurate reading. I would just stay away from SpeedFan, as in my experience it isn't as accurate.
Core temp should work fine. It will ask you if it can make changes becuase it access hardware. I use Windows 7 64bit with a C2Q. does it for me.
I've not tried Real Temp on this machine so I can't say.