How to View DVDs on Your Hard Drive with Windows Media Center
This page shows how to view DVDs that are stored on your local hard drive using Windows Media Center (WMC), Vista version.
If you have created, ripped or backed up DVDs on your hard drive and tried to play them in the Vista version of Windows Media Center, you will probably find that it doesn't work. When you try to play a DVD, WMC tries to open the folder and tells you that it's empty. This is because, unlike previous versions of WMC, this isn't how you play DVD folders in Vista.
Rather than playing DVDs from the Videos section, you need to use the DVD Library which is located in the TV & Movies section. If this is not enabled (i.e. you can't see it in the main menu), you need to edit the registry.
Warning: Editing the registry is for experienced users only. Inexperienced users can cause serious damage.
Here is the required registry edit:
Registry value: ShowGallery
Registry value data type: REG_SZ
Registry value data: Gallery = enable My DVDs; Play = do not enable My DVDs
Change the setting to "Gallery", reboot the computer and restart Media Center. You should now see "dvd library" in the menu. To add DVDs, go to the information menu (click "i" on the remote control) and select "Add Movies".