512
ATI 9800 Pro
1280x1024
All in game sliders set to max detail
I tried 1024, the graphics were great, but I experienced an occasional slight hesitation when approaching some enemy planes. Not nearly as bad as the horrible screen freezes on my old system, but enough to bug me. So I switched back to 512.
I might try disabling custom skins and going back to 1024. But realistically the only time I can tell the difference between 512 and 1024 is looking at my own plane, or an allied plane right next to me. You're never that close to an enemy plane for long enough to see the difference, and I saw no difference in the ground textures.