this should be an easy enough question to answer

i have video
i just want the sound from it
it is in avi format
what editing program(s) should i use and how should i go about doing it

also: i would like to combine this track with perhaps multiple others, for which i will probably be using audacity if possible
pandora.com for kick ass free radio.
is it free?

EDIT: no it's not... never mind

is there a free program that will do this for me?
pandora.com for kick ass free radio.
You can do this in Audacity, just set the input to your soundcard (so it records every sound your computer makes), then play your video file.