Video collage/mosaic effect

[purplegreendave]

So far, Avidemux is an amazing tool for making my club-trip videos (where we collate the best bits of the kayaking, camping & drinking from the trip into 1). I do all my editing in avidemux and then stitch the edited videos together with movie maker.
One thing I'd really love to do is make a collage/mosaic 4 videos together, ie video one in the top left quadrant, video 2 in the top right quadrant etc.
Is there any way to do this, or can anyone suggest a tool/program that would enable me to do it?

[purplegreendave]

Aha, found something that should do it:
http://avisynth.org/mediawiki/StackHorizontal