I used simpledivx for a long time for movies, but ran into problems when converting 30fps material. It was locked into 24fps and had 6 skipped frames per second leaving the video a bit jerky. AutoGK is probably the best as far as freebies go. Nero Recode is also fairly decent, but slow as heck. If SimpleDivx is ever finished it may well be the most powerful/easiest to use since it uses Mencoder. AutoGK uses VirtualDub for most of it's video conversions and seems on average a little slower to me.