fixing audio in AVI files

I have some AVI files and the audio volume is really low. Even with my PC speakers turned all the way up, it's just not loud enough. I have run some through Virtual Dub, but I have to use full processing mode which can double the size of the file. It's OK if the source AVI is under 300mb or so. But I just did an audio volume 'fix' on a 530mb file, and the finished product was 1.32gb!!! There's got to be a better way, if not with VDub, then maybe with another tool. I see 'Avidemux' here at MajorGeeks (link http://www.majorgeeks.com/Avidemux__d5930.html ) and that looks like it would work, but I haven't messed with it yet. I figured I'd post here first. Anyone have any ideas on how to adjust the volume so it's louder? I mean really adjust it... like by 300% or 400% or more in some cases.

Thanks.

 

EDIT (or UPDATE :confused )
Apparently, the built-in Windows Movie Maker has an option to do this. Having never used WMM, I did some research. It's actually fairly simple, but when all was said and done, it said it would take 224 minutes to save my movie!!!! WHAAAAA?!?!?!?!
I'll say it again... there's got to be a better way....