Hi, I'm new to this forum, but I thought I'd start myself off with a question I partially know the answer to. I'm deciding on the premium model MacBook Pro, and I notice the option to either do the 750GB @5400rpm or a 500GB @7200rpm....My question is, what's better for speed? I'm not to picky on the hard drive as the Dell I'm using now is a 250GB and it's sure plenty. I figured it'd be the 7200rpm one...but the second part to my question is: How big of a speed difference is it? A lot, tiny, huge, MEGA, what?