The new iMac is great unless you plan on installing Windows and playing this years games. In that case, with the Radeon 4850 512MB, you won't be running any of this years games at native resolution without turning AA off and all of the settings down.
i have that card on the older iMac and i can play cod: waw at full settings, 8x AA, 1920x1200, and it runs fine. arkham asylum runs at full settings as well, and crysis runs 1280X800 2X AA, which isn't bad at all. What were you saying?