To get an audio-only file: guide at http://www.dvd-guides.com/content/view/136/59/
found via videohelp.com - the guide uses DVD Decrypter and Goldwave, I used WinAmp with Disk-Writer plugin instead of Goldwave for the .wav conversion. Initially, the WinAmp playback of the mp2 file and saving to file was buggy - clicks at every second or so. Found that it was playing back fine in Windows Media Player. Found some info at this page - http://www.free-codecs.com/download/MP4_Input_Plugin_for_Winamp.htm leading me to remove the mp2 extension in the list of the Nullsoft MP1-MP2 plugin and add it to the Directshow plugin instead. Then it works fine.
Ctrl-P in WinAmp -> Plug-ins -> Input -> Choose relevant plugin, hit the configure button, add / remove extensions in the File Association Extension list.