I have been planning on getting an iMac for the last 6 months, and I have gone as far as ordering it then canceling it the next day, now I think I'm sure I'll order it, but what difference other than screen size and processor speed would make to me, I plan to use it for web surfing, mail, MS Office, iChat, iMovie, no videogames at all, would like to view HD movies if possible, now $400 is a big price difference to me, so according to my uses, does the $400 difference justify the 20" for MY uses? thanks