Codecs

I’ve been having trouble playing video files on my comp for a while now, and I know that I need the proper codecs in order for vids to play properly. Now with most AVI files my computer will play the sound, but no video. Is there a website that you can download a codec that will fix this? I’ve already tried codecs off BearShare and other P2P networks and none of them worked.

Thanks…exactly what I was looking for.