To get a decent experience with the type of games that you mention, you will definitely need to be using Boot Camp. This allows the Mac to run Windows natively without any of the slowdown associated with a VM system.
Case in point, I have a copy of Call of Duty, Modern Warfare 3 which runs at full everything using Win7 on Boot Camp on an iMac i7.
The same game, on the same iMac running XP under Parallels, is not really playable. It works fine on the opening screen but as soon as I move into the main street, where the action starts, the whole thing just slows to a crawl, and that's with everything turned down.
Given that information, the choice of Windows OS is moot as Boot Camp only supports Win7 and, maybe, above.
P
Hello everyone. With Windows 8's metro UI completely turning me off, I was wondering which version of Windows would be best to run on Bootcamp and/or Parallels Desktop 7 (virtualisation) for games?
My brother swears that Windows XP is still the best for gaming.
Windows 7 on the other hand, seems to be the latest "stable" version of Windows.
Now despite the ugly metro UI, if Windoze (oops)8 runs games any faster... then I might ~actually~ consider that (when Mountain Lion comes out, I'm sure it'll support Win8, right?)
The games in question? The really heavy ones of course! Diablo 3, Dirt 3 (or 4 when it comes out), Need for Speed, RAGE... those kinds of games.
Currently running Lion (10.7.4) on an 2.2Ghz quad-core i7 (early 2011) Macbook Pro 15" (with 1680x1050 resolution), 1GB Radeon 6750, 8GB RAM.

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