I have the 30" HP LP3065 and 8800GT. All of the mac-standard resolutions show up in the displays panel. The video card is doing the scaling, there's no slowdown that I've noticed, even when 3D gaming at non-native res (1920 x 1200, or even 1600 x 1200). DVDs look great. In the past I've always favored ATI for DVD playback, but this card doesn't disappoint.
If you don't need any other types of input source (component, etc), this monitor is an excellent choice. Near-black screen, great contrast, none of the graininess that I saw with my Dell 24".