To convert a DVD (or ripped files from a DVD) to DivX format (smaller size, great quality), you’ll need a program called SimpleDivX. It’s free.
You can find a guide on using it here, but here’s a teaser…
“This guides shows you how to convert a DVD to DivX / XviD in some simple steps. This is version 1.33 but you can get a newer version (1.34). I have decided to show you this program as this is very good and unlike FairUse Wizard you can burn VOB files already burnt onto the pc. If you want to do this, read Afonic’s guide about ripping a DVD to the Hard Drive of your PC here.
This software leaves excellent results especially using the XviD codec. Sadly for some reason 2 pass mode on DivX will NOT work on my but on XviD it does. Anyway XviD is known to be the best codec so lets get on with the software outlook. Make sure you have the XviD or DivX codec installed on your PC beforehand to avoid confusion”