Handbrake for the Mac is the first software I've ever used that converts movies in a very simple one program process that turn out a micro step shy from my portable dvd player. I've used other products before but Handbrake is free and I just created a StarWars movie file that is 220 megs and a Polar Express movie file that is 190 megs and neither flinch, pause, or stutter at anytime even during the most intensive action scenes. I'm loving this. Here's a link with some screenshots and how to download. Cool program.
http://handbrake.m0k.org/?page_id=25