Having trouble with a laptop (it's a mates)

It's running VISTA and it will not play DVD's at all (in WMP)....i've done a bit of research and it seems it needs a codec for it to work?? any1 know where i can get a codec that is guaranteed to work? preferably free and downloadable too lol.

i think it's disgraceful these units are sold with programs/software/hardware that can't be used!!

I don't particularly want to load another media player onto it, but if that's the only solution i will....but it must be able to utilise moving videos about onto I-Pods etc, as his daughter wants to do that.

any help would be greatly appreciated