Xvid codec?

I am trying to play a movie, and i have windows media 9, divx 2.1 and 2.5 and i get this error message:

'Sorry the file could not be opened: You may need to download a new codec to play this file. Above it mentions FOUR-CC Xvid 5..

i have the divx four cc codec from this site, but it still REFUSES to work.. yeah and my pc is fast enpugh to play it.