WMV Converter

What free software can I use to convert avi/mpeg to WMV? I want to play music videos that I’ve downloaded from Limewire (which are all mpeg/avi format) over the network on my Xbox 360. But the xbox only plays WMV, I’m assuming because its Microsoft. Movie Maker does not work, says the movie files are corrupt. I just want a plain simple converting program. Any ideas please? Thanks.