|Be nice. It isn't rocket science, but matroska playback can be problematic--especially since the h264 codec started becoming more popular.|
I don't like codec packs. I don't use them. That said, here's a minimal pack that will install Zoom Player and set your machine up for avi/ogm/mkv playback with multiple audio/subtitle streams, blah blah blah. It also uninstalls cleanly.
"If it ain't broke, upgrade anyway."