I recently bought a Phenom II 965, and paired it with my HD6750. I am running these settings in BF3 and getting 40-50FPS:
Resolution: 1440x900
Field Of View: 85
Textures: Ultra
Shadows: High
Effects: High
Mesh Quality: Ultra
Terrain Quality: High
Terrain Decoration: High
AA Deffered: Off
AA Post: Off
Motion Blur: Off (It doesn't effect FPS, just annoys me)
AF: 16x
Ambient Occlusions: HBAO
This is one great processor, and the HD7750 beats my HD6750 even though I've OC'd it from 700Mhz to 776Mhz. Don't go for the APU since you won't be able to use hybrid crossfire because the 7750 is not compatible with the integrated GPU.
Hope I helped!
~UnlimitedBanana