Here is my Windows 7 Experience Index using the stock graphics driver:

And after installing the newest driver Forceware 197.45, it becomes:

The only change is that the "Gaming graphics" subscore drops from 6.4 to 5.2.
Is the stock graphic driver more optimized for Windows 7? Or is Forceware 197.45 buggy? Should I revert back to the stock driver?
My configuration:
- Athlon 64 X2 5000+
- Asus M2A-VM (AMD 690G, SB600)
- 6 GB DDR2-800 RAM (only 3.25 GB usable under Windows)
- GeForce 8600 GT (256 MB)
- Windows 7 Ultimate 32-bit

