After comparing mpeg4-2, divx, and real producer I've concluded that real producer does the best job with size vs quality. If you blow each up full screen (ctrl 3 for real player) and watch carefully around the outline of the plane you'll see more compression artifacts in mpeg and divx than with rm.
If anyone knows how to add sound to rm files without dropping $200 for real producer plus I sure would like to hear it. Not interested in warez.