I'm considering investing into one of those as well, but I'm pretty broke right now

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I'm sure that the newer generation MacBooks (more specifically the newer MacBook Pro) run the game even better than mine does.
I forgot to mention that the Mac SC2 client seems to run a little worse than the PC one. It's a bit choppier, if anything. Other than early beta issues, I've had just about zero problems with the Mac client--less than the PC client, to be honest. When I close SC2 it sometimes slows down my computer for a minute or two, but I notice that with a lot of games.