Thins you want to download
plays every divx i ever had but has weird interface
to play in quicktime download the codecs(they are like plug ins) form 3ivx.com and divx.com(this codec iis included with a program that will make the files playable and still be able to play on windows if ya wanna swap.)
to turn a divx into a quicktime get divx doctor.
hope this answers your questions.
videolanclient is the only viable divx player on the mac right now (www.videolan.org). Codecs are essentially plug-ins for media apps that allow you do encode/decode(play) certain types of audio/video. back in quicktime5, the divx.com codec or http://mpeg4.jamby.net codec could be placed in the /library/quicktime folder and would allow you to play divx files (no encoder unfortunately) perfectly in any app that supported quicktime (so you could watch full movies in the preview column of the finder and cool tricks like that) as long as you changed the file type to "DIVX". with quicktime 6, these codecs no longer function properly and you have to use conversion programs to modify the audio tracks of the movies (essentially creating a duplicate of the movie) if you want to play them in quicktime, which is not all that convenient as it requires you to have two copies of the movie. vlc plays divx, 3ivx, msmpeg, vcd, dvd, etc. files perfectly, without modification, but you still lose support for quicktime apps. hopefully someone will fix the divx codecs to work properly with qt6, but i'm not holding my breath.
edit: all of the mac codecs are currently encode only (you cant convert a movie to divx with qt6 like you can with mpeg4, sorenson, etc.). if you want to encode divx files, you'll have to download ffmpeg (available on versiontracker), although i'd like to see more people start using true mpeg4, rather than these bastard variations of it (that way you would not need all of this extra codec buisness).