You are trying to see the DVD with Windows Media Player, and that might be your problem. WMP cannot play DVD's out of the box because Microsoft does not include MPEG2 decoder with any installation of Windows. The decoder comes with third party DVD player software, or it can be purchased separately. You can buy Sonic Cineplay, PowerDVD, WinDVD or many other DVD playback software packages. Once insalled WMP will have an access to MPEG2 decoder and will play DVD's.
If you have a third party DVD software installed, try some Holywood DVD's. If WMP is playing those, then you probably have a problem with authoring package that you have used to make your disc.
There is a free universal video player called VLC that will play almost any video and audio file, although it won't make WMP DVD-friendly.