In principal you can play matroska files on almost every Mediaplayer on .... the codec on your Windows PC, and VirtualdubMod will be able to open any AVI ...
After that, you can just double-click an MKV file to have it open in VLC. Of course, not everyone likes VLC player. If it doesn’t suit you, the Matroska website offers a few suggestions for media players for Windows with built-in support.