You may want to try the DivX player from here http://www.divx.com/divx/player/

Ivan
In the dark we make a brighter light

Apparently the links for those codecs are dated. The 2nd one will work; Mirror2.

There's also http://www.free-codecs.com/ & http://www.click-now.net/html/K-LiteCodecPack.htm

As Backmann suggested, it's a good idea to have more than one player as a backup. Some people use a few just in case.