On you ATI card settings, adjust the sliders higher. Granted the crisper the graphics, the FPS go down. But you can find a happy medium I am sure. I am not sure if the sliders are the same as my card, but I have the AA around 4 and the Aneospheric thingy around 8.
Also if you open up the FS9.cfg file, you can edit the parameters under the display settings. Expand the radius so that the textures appear more clear around you and tapper off in the distance.
In the game I don't set my Mip levels more than 4. 5 and higher do give me a headache also.
