Want to play a DVD movie on my computer

Seems to me I used to be able to watch DVD's on my computer before I reformatted XP some time ago---I have a Dell XPS 410---Window's XP SP3---it only has one disc slot on top which I use to download stuff and listen to musical DVD's---the movies will not play in Window's Media Player or in Winamp---is there a program I can download that will automatically pick up on when I put a movie in and let me play it?---thanks for any help---oh, I use Firefox if that makes any difference

 

Hmmm---downloaded it and still cannot get anything---no biggie---have a little portable DVD player---just thought I could get it on computer---thanks

 

I don't know about automatically picking up and starting but KMPlayer will play a DVD. Just install the player, start it and right-click the window and select Open and choose DVD. It will open a DVD that is in your drive.

VLC player also has a DVD option. Both have the codecs built in to the player.

 

Many thanks to all---tried all and got could not open errors on each---maybe I never watched a movie or DVD on here---thought I did long ago---perhaps that slot on top isn't a player after all---hmmmmm----my roomie has the exact same computer ---except he has Vista instead of XP---cannot get his to work at all either---sooooo---thanks---and I will stick to borrowing my roomie's portable DVD player---