Oops. That was what I meant to put in my first post instead of Avidemux.
Avidemux is a video editing program, not a sound editing program, though you might be able to clean sound up with it.
Audacity is the fun little sound mixer that I used for my 2 or 3 little Star Trek flyby animations that I did. It's a cool little program. I just got it confused with Avidemux because I got a buttload of digital media software on a CD from Maximum PC and I've installed the more useful tools, like Audacity and Avidemux.