Ripping is the process of taking the data of a disk & copying it to your HDD. DivX is a video format that's based on mpeg4 (the higher the mpeg no. potentially the better.) It's a very popular format for converting video to, particularly for transporting across the web. It is more space effective than either mpeg 1 or 2. As a general rule, divx are better than 3ivx or mpeg1 conversions. But then again, divx can be any resolution & it depends upon what it's been converted from (the source) & what quality settings have been applied during the conversion.

mpeg 1 is what's used for vcd. mpeg2 is what's used for svcd & dvd (when you said mv2 I think you meant mpeg2/mpg2 & also mpg.) AVI is an older ms format. It's like Qicktime in that it's an outer shell. The contents of the 'egg' could be any of a no. of formats. You can have avi-divx format for example. MOV or moov is generally a QT format movie. I'm not so sure on the definitions used over the net.

Which one you should use depends upon your needs!!! If you wish to burn it, well it depends upon your burner app. & what it supports. The better burner apps will accept avi & mpeg (be that 1-4). If you only wish to view it on your computer, then it doesn't really matter. So long as you have a player hat can play them. For burning movies, make sure they're a minimum of 500 mb in size otherwise you're going to end up with very poor quality or spam/rubbish.