windows can't ever open video files

Hi,
I have tried opening various video files from some of my yahoo groups. In every case, Windows says it can not open them, needs to know the type, etc.
They are mostly mpeg files. I downloaded winamp3 to try to open an mpeg file and that failed too.
These groups would not have files if nobody could open them. What ways are others members using to open them?
Thanks.

 

http://www.divx-digest.com/software/nimo_pack.html

site above has the nimo codec pack.
site bellow is a much better player than win media player.

http://www.divx-digest.com/software/bs_play.html;)