I had the the 27" iMac with the ATI and I just recently ordered the 15" i7 MBP with the 330M (512MB). Knowing mostly nothing about graphics cards or computer gaming, but wanting to get a few games for my MBP, I'd like to know how the 330M compares to the Radeon HD 4670. I intend to get Orange Box for Mac when Steam's out and the Mac version of Call of Duty 4: Modern Warfare. My only experience gaming on the iMac was a Bioshock demo that ran modestly on mostly medium settings. So in comparing the two graphics cards, I'd like to get a sense of what to expect. Thank you.