Just so you know, if the dvd movies you are referring to came from say a commercial dvd in a store (Blockbuster for example) and/or were downloaded via filesharing, the process of copying them, breaching copyright and copyright protection is not legal and so you will not get an answer in this forum.
If you created the dvd movie yourself with MyDVD, "Pimp's Spring Break '06" and want to know how to play from the dvd folder before burning, that could be answered.
As a general comment, WMP is OK as a one stop player but there are better music and dvd players around.
Starman*