Looking to get my first mac & due to my needs, researching MBP's. Processor speeds aside, I'm looking at 2 particular models - one has a 512mb 9600GT & the other has a 256mb 330M. Which GPU is better? (i.e. does the lower vram hinder the newer video card) On a similar note, what's the lowest MBP you'd use for HD video editting? Thank you!