No sound with DVDs

I have tried in vain checking all my settings, but no luck…My problem is that I want to watch a DVD using either Windows Media Player or Real Player but I get no sound. The picture is perfect, however. The only way I can watch and listen is by opening VLC player, but then I can only access the dvd via each VOB file individually, and sometime the sound starts, then there’s a pop, then it continues, etc. can someone direct to how I can get both picture and sound using WMP or RP? Thanks.

you need the ac3 codec, get it here

THAT WAS IT!!! Thanks very very much!