Need to import video via iMovie and play iTunes simultaneously...

Yo there, Mac forum! I'm a new Mac user and am pretty dang psyched to be posting my first question. I love my new PowerBook. woo!

So I'm in an improv comedy troupe and I use the PowerBook to play music and sound effects during our shows. I also video tape every show for us to watch at a later date to assess our performance (like football coaches do). I would like to stream the video directly to my Mac, so at the end of the show I'll have a digital version of the show nullifying the need to perform the intermediate step of digitizing it from the cam sometime later.

Now, using iTunes to play music during the show is simple. Also, using iMovie to copy video from the DV out of my cam to the hard drive is also simple as cake. The TRICKY part is doing both at exactly the same time as they both send audio signal to the minijack output (or speakers). That causes not only the iTunes music and/or sound effects to be played back thru to the stage, but also any sound that the camera picks up will also playback--which as any of you sound people out there know, causes some funky feedback and resonant effects since the cam is also picking up the iTunes tunes and sounds. Phew.

SOOO, does anyone know how I can can capture live video to my harddrive (to a file or movie project) where it does NOT send audio to the notebook speakers or minijack out so that I can utilize iTunes to be playing the music for the show while the video (with it's audio) is streaming into the mac "behind the scenes" in the background?

A lifetime of free tickets to our shows if you help me solve this!

Cheers,
Tom J Schaeffer
The Originals Improv Comedy Troupe
Phoenix, AZ
www.theoriginalsimprov.com