Try KMPlayer. It's like a cross between MPC and VLC - it's MPC with its own internal codecs, sparing you of the trouble to look for codecs, which really is a pain in 9x/me. Plays almost anything on my laptop in sig, only things it couldn't recognize were 3GP movies filmed with my cellphone, but i'm sure there are updates for that. It also has a lot of settings, allowing you to choose various filters, better video/audio quality or faster rendering speed/lower CPU usage, basically everything you will ever need.