So I'm buying a MacBook, and am really strapped on a tight budget here. So I can't decide between the two MacBooks, the 2.1 and 2.4 GHz models. For 200 more, you can get the upgraded processor and an extra GB of RAM... So I was wondering, how much more performance will I see in the 2.4GHz model? I was planning on dual booting XP, and running some older Source games like Counter-Strike. Normally I'd just go with the 2.4 GHz model, but can someone tell me from personal experience or knowledge if it's worth it to move the budget up?