My personal reason for running XP on my Mac is strictly for gaming purposes. Why have a PC just for gaming running XP and a Mac running OS X for everything else, when I can just have a single Intel powered Mac which runs both? For this reason, Virtualization software has been meaningless to me as it generally doesn't offer any 3D acceleration. But with Boot Camp, everything from Rome Total War to Elder Scrolls Oblivion zips along nicely on my iMac 2.0GHz.
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