Which version of Windows runs best on an early 2011 MacBook Pro (and how do I obtain it)?
Looking at the Bootcamp 5 FAQ - you want a 64 bit version of Windows 7 or 8.


http://support.apple.com/kb/HT5639


Furthermore, you'll want to get your specific model of MacBook Pro and check this table for the exact version you want before shopping:


http://support.apple.com/kb/HT5634


As for major version, I know many businesses that stuck with Windows 7 so unless you need Windows 8 - I'd vote with my wallet on the cheapest non-XP version you can get. From your question, the home version is perfect for gaming and you won't really need advanced pro/premium features based on the requirements (actually lack thereof) that you listed. A benefit of going to Windows 8 now is that presumably you'll have longer to run with it before needing to upgrade to a future OS. Mark also makes a good point that Windows 8 is marketed primarily to consumers as an upgrade version, so be sure you understand your return options when buying and check into a Windows 8 system builder / OEM version if you decide to go with 8.