Most likely you could get K lite codec. Click here to get
http://www.free-codecs.com/K_Lite_Co...k_download.htm
This has all the codec you need to allow you to convert. Also you could use VLC media player to play your movies. Thats what i Use at the moment. Also if your tired of windows media player using your ram and causing you constant freezes you could use foobar. Its uses less ram and you could amp it a lil to hear great quality music.