Have you checked what others are scoring?
I can tell you as reference some AMD physics scores, 3dmark11 on win7:
FX4130: ~3.5k
FX6300: ~5.2k
FX8320: ~6.6k
FX8350: ~7.7k
Also, windows 8, at least on AMD CPUS, scores quite lower for physics than windows 7 (300-400 lower) No, I didn't read it on the web, I saw it myself. Same systems, hard drive swap, run 3dmark. The graphics score is higher in win8, but the physics score is lower, and for 3dmark11, the difference in gpu score is not enough to compensate for the quite lower physics score.
What I observed is that the overall P score tends to be higher on win7 for 3dmark11 (physiscs being the cause) while firestrike is higher in win8 (not as big difference in physics)