Stuttering

Hey,

Anyone know why the movie stutters when I use windows media player.
I know the file isnt corrupt because it works on my friends computer.

How come when I play videos that has been ripped from dvds, it stutters.
If u know why. PLZ HELP.

....

I found out it doesnt stutter when I use DivX. But when I use windows media player or BSplayer, it stutters. Anyone know why? is it maybe with codecs or something?

Also, about my hardware.. . . I have a fairly new computer. Its a Sony Vaio, 2 GHZ. 512 megs of ram. for my drivers i think i have some intel graphics controller thing.
Anyone with any help. .. plz help...