Arr. I got DivX to work on Debian just a few days ago, but it was all a bit weird, even though apt-get helped a
lot. Basically, install
xine. I think it does DivX out of the box, so you'd be set. There's also
mplayer, which is supposed to be better than xine, but I was too dumb to get it to work (I'm
very new to Linux). There's also
avifile which seems to be a library, like an actual codec, that plays a range of source files. I don't know that fits in or if it's a mandatory install, but since it was a matter of a simple apt-get install avifile-something, I did it just to be sure.