I would like to be able to convert commercial DVDs (from my own library) to mp4 files for viewing on my Ipod Touch while working out.  I searched for DVD conversion programs and many popped up...most offering free trials.  I tried a few out and got mixed results with them.

Knowing the people on this forum have lots of experience I thought I would ask:  Can anyone recommend a good tool for this purpose?

 Also interested in converting mp4s to avi.  Any good tools for this? 

Thanks!