on the mac vob files are handled by quicktime, if you have qt pro you can save the audio data as an aif or wav etc and then onto a mp3.
with the pc there are many programs that will convert mpeg2 data to say avi and then you would require a video editing program to select the audio tracks and export to wav and then onto mp3.
type wav to mp3 into google, theres a free one around but do a spyware check straight after installation as it also adds a few unwanted goodies.
http://www.mthreedev.com/ is what i use on the pc to convert wav to mp3
do a google search for mpeg2 to avi or dvd to avi
virtualdub should allow for the audio extraction once its an avi etc..
you will need a lot of hard drive space for this type of conversion (hence the avi size and then the wav size )unless you find a all in one ripper/converter etc..
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