using audio from avi's is generally a bad idea because it's generally low quality. i suggest searching for mp3s encoded from audio cds (through a p2p network or otherwise). if it's love addict you're looking for, i do have that mp3 (pm me if you cant find it anywhere else cause i dunno where exactly it's stashed)
but yes, of course it's possible to get the audio seperate, since all avi is, is a container that holes an audio stream and a video stream. you can use virtual dub or premeire or something similar to take out the audio from an avi.