Make WMP play ANY Video (like VLC !)
I've been using this software for a long time, and essentially it installs every codec you could possibly dream of, into Windows Media Player. It means you don't need to have a seperate player for XvId and FLV files, instead, you can play them all inside the built in Media player.
It's called the "Combined Community Codec Pack" (CCCP for short) and comes bundled with Media Player Classic (a bare bones version of WMP) bundled, if you so choose to install it.
Check it out over at CCCP Site