hey can i just ask i am going to buy my first mac and im thinking of getting an imac 20inch core duo model fitted wih 1gig of ram and am thinking about the video memory upgrade. the main purpose i will use the computer is for imovie and abit of ilife, not so much in games. so is it worth the upgrade to the 256mb of video memory,? will it really boost performance in imovie? Cheers!