Hi Sheree,
There are links for codecs for WMP in this thread. Also a link to VLC player, which a lot of people like.

http://www.gnutellaforums.com/showth...ght=wmp+codecs

If you want to know what codecs actually are, there's a simple explanation here:
http://www.sharpened.net/glossary/definition.php?codec

*sorry...forgot to paste in the thread!