Why does my PCs DVD drive not work?

Windows doesn't come with a proper DVD front end. You need software like Cyberlink Power DVD or Intervideo's WinDVD to be able to play a DVD on a Windows PC. Mac OS X has it built in, and in Linux you can cobble it together in an afternoon from illegal download sites (Here in the good old USA, anyway) on the interweb. If you get hold of either program, you should be able to insert a DVD and just watch the movie.