[Tom Smarch]

Open your .AVI file in Sound Forge. Select the entire file and save it as wave file. The audio will be saved in a seperate wave file.

Now open up your .AVI file in Movie Studio. Ungroup the video and audio files by selecting them both and hitting the CRTL and U keys. Now delete the audio track, but only after you unselect the video portion. Now drag the wave file underneath your video track and you are good to go. You can group them together again if you want to be selecting the video and audio tracks and then hitting the G key.