MP4 Clip / Windows Media Player ProblemSurfing Tips
DiVX codec should work, as should FdShow.
There is also a free program called Format Factory which is worth having. Not only does it convert any video to any format, but also does music files.
(ie iTunes Mp4a to whatever you want -which is supposed to be impossible.)
Best of all, it's a retard proof drag-and-drop program. Amazing. =)