Mainly the difference between the high end Macbook and the low end Macbook Pro. I can't really see any difference except the screen size and graphics card (and hdd which you can change anyway). I have an older MBP and is thinking of swapping to the newer version but if they are pretty much the same machine I'm not sure anymore. The smaller system would be nicer. With an extra screen at home you have the best of both worlds. Light to carry with you and a bigger screen at home. I'm using it in a music studio so 15.4" is cramped as it is already, and I really need the horsepower. To further bog this down my extrernal hdd and soundcard both use Firewire (400 and 800 respectively), but they can be run with usb aswell so no biggie. Should the high end MB be considered a 13" MBP?