Hi Jack, congratulations for getting an iMac. I'm sure you'll love it!

Regarding your video editing plans, it may be of interest for you to watch the keynote that Phil Schiller from Apple held at the recent NAB conference in Las Vegas. He introduced the forthcoming new versions of Final Cut Pro (4) and DVD Studie Pro (2). Both programms will also incorporate a brandnew software mpeg encoder called 'Compressor' that is supposed to be very good and fast.

http://www.apple.com/quicktime/qtv/nab03/