I'm currently on a rev a unibody macbook (core 2 duo 2.0ghz w/ 2gb RAM) and i've recently been upping my video editing usage. I'm editing hd (1920x1080) in final cut express and it is going to drive me insane if i don't get a new computer (cue the tax return fairy). Most of my videos are around 10 minutes and just to drop a background into my keyed video takes an hour to render before I can continue to edit/playback. That being said, I was originally thinking iMac, but I know I will greatly miss the portability of my macbook. Does anyone have experience editing HD green screen work on an i5 Macbook Pro? Is it simply acceptable or actually good. I'm thinking that unless it is good, an i7 iMac that I could get for within a couple hundred of the price would kick my editing speed up to a high enough gear that i would be willing to sacrifice the portability - any thoughts? Thanks!