Windows recommends a resolution of 1280x800, but it seems to run fine in 1920x1080--HD res--though there are letterbox bars at the top and bottom of the screen. 2560x1600 is the native resolution, which is also recommended by Apple. At that resolution the image is crisp, but I get about 30-40 FPS out of WoW. There's an approximate acre of desktop at this resolution, though.
This is going to take some adjustment, and not just on the computer's part.