avi2mov and getmp3 should not be in qt library...
those two are tools that you can use in the terminal...what you do is drag EITHER one in the terminal, then you movie, then type desired location and name of the new file to be created "xxxx.mov or xxxx.mp3"
the .mov file should play fine and hopefully it does cause cause it takes longer for getmp3 to make the mp3. okay so if it doesnt work you need to do the getmp3 thing...this will take a little bit so hang in there...when it is finally done, open in it qt pro, extract the sound track....open your original.avi and do a "scale paste" of the sound track over the video and disable the original sound track...this should work well....
hopefully apple will fix the avi audio problems so these steps wont be so necessary.
also, one last correction, you cant watch all .avi's in QT OS X...yes for divx, but normal .avi's dont work....
hope it all works well for you....