u can't go higher on General Drawing Quality then 8 and still expect your system to run well.
i'm using 2 gtx460, i have all settings maxed out including AO & DoF, i lose about 5-15 FPS outside of towns, so 45-55, but that's fine.
i think someone has explained it somewhere before, but general drawing quality is like a multiplier of your resolution.
if you play on 1920x1080 with DGQ at 8 the quality is according to your game's res, at 9 it's x1,5 and at 10 2,0.
so 10 is like playing the game at double of your resolution.
in the beta it was called window buffer size, turn of your AA, and check the difference from 8 and 10, i think that's the best way to see the difference.
Ninja Edit:
here 2 examples.
1st, GDQ 10, DoF, AAx0
http://i74.photobucket.com/albums/i2...1304789768.jpg
2nd, GDQ 8, DoF, AAx0
http://i74.photobucket.com/albums/i2...1304789908.jpg