I have xp on my laptop whith close to 400gb of games, I have 7 on my desktop and it's great, but I really cant be bothered reinstalling the OS on my 13inch laptop, which is a MBP (13 2010), which means I need to go through bootcamp, even more effort. in the end it's just laziness I suppose, I don't want to spend 2 weeks tracking down all my disc boxes, and re downloading all the updates, for what, a slight speed increase, I am on a 13inch laptop, any game that uses a lot of dx10 features it wont run very well (I was able to get crysis 2 running at 30fps thoug, but it's dx9)
And I know a Lot of other people are in my position too, I have recommended xp to freinds only a few years ago becuase it cost $50 vs $250 for w7, when they barely play games.
I primarily use my desktop, but it's sad I wont be playing games on my laptop