You can run it at 1280x1024 all settings high, 8x anistropic filering, and 4x FSAA easily. It depends on ur monitor size though.
For 17inch i'd recommend 1024x768 w/ all settings high
For 19inch i'd recommend 1280x1024 w/ all settings high.
I used to have an x800 pro and I ran that game very smoothly at 1280x1024 on a 19 inch monitor w/ all settings high and 4X FSAA.
-mpjesse