I'm thinking of switching my Lenovo Thinkpad T60 over to a MBP. I want to get one of the 15 inch MBPs. Is the performance difference between the lower end and the middle one that much (or at least worth the $500 price difference)? Also, my T60 is based off the previous generation Core Duo @ 2.0 Ghz so would there be a huge difference between that and the new 2.2 Ghz Core 2 Duos? Can you run Bittorrent on Macs? What about AVI files (for my pRon)? Help! Much appreciated!!!