Unless I'm mistaken, the Phenom and Athlon series are both AM3 socket CPUs, so I'd suggest saving the money and just getting the Phenom. I'm currently running the Athlon II X3 at 3.0GHz, and have no problems. Windows 7 Ultimate (x64) gives me a rating of 6.8 out of 7.9, with my CPU being the lowest rating.
64GB Samsung 830 SSD
1TB HDD + 40GB Page File HDD
nVidea Geforce 560 TI 1280 GB (ASUS)
14GB DDR3 1066 CL7 Ram
What games are you playing? With this setup, I'm playing Skyrim, Portal 2, StarCraft 2, C&C 3, and Duke Nukem all at their respective highest graphics settings.