Perhaps something along the lines of DVDCutter Stream and Mp3CDWav Converter Pro 5.01 or Plato Video Converter? I haven't used either of them before but both have good user reviews and offer free trials.

One note, though: Every time you convert a file you will lose some amount of quality. It is usually minimal provided the format you are converting to supports the same quality as the original, but only convert as necessary.

John