OTOH, I fully support the Shark007.net - Windows 7 Codecs
by Shark007 b/c they work.
incidentally, one of the formats that also uses the .AVI container although the codec is proprietary is DivX - and the Codec Pack works just fine.
In opposition to Baarod's comments, I prefer being able to play files in their native codec format as opposed to having to convert them to another format - hence my desire for a codec pack. The *only* pack I trust is the one I mentioned above b/c it is basically a collection of tools from around the Internet all of which have been tailored to work with native video and audio playback in Windows 7. It's not perfect by any means (e.g. FLAC audio in WiMP plays perfectly fine - except for the seek bar not moving at all), but it works without having to do a lot of conversion.
My main aversion to converting videos is that codecs compress the video, and often with loss - and converting from one format to another will almost always result in *some* clarity loss of some type. however, if this is what you prefer, then AVIDemux is pretty much the way to go - either that or MediaCoder.