Everyone rags on ATI's OpenGL performance; yet I ran D3 at 1280*1024 high with my 9800 Pro 256 MB.
Personally I think the days of driver support being an issue are gone (except for linux support).
I think ATI still leads the way in performance, not because they are better at the moment (they aren't) but because they are posting scores close to nVidias cards while using alot less power and cooling.
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Gameplay before graphics.