I tried AoC tonight with the same settings I was using on my GTX 280 with an 8800GT (700|2000) @ 1920x minus AA
and it could run it @ 34-56FPS in Khopshef. I am returning/refunding the GTX 280 and getting an XFX GTX 260. I ordered the 260 tonight and am shipping out the 280 tomorrow.
The 260 should allow me to start using AA again over the GT and inflate FPS a bit.
For the record the settings were bloom on, shadows all enabled, ground quality distance max, all the other distance and details sliders were max except grass, which I kept at 50%.
Look here for a comparison of a GTX 280 @ 700 on the core and a GTX 260 @ 640 on the core-
If you play 1920x and under you'll never feel the difference.