For owners of ATI Rage Mobility-128 AGP 2X, and perhaps other cards from ATI, here's a tip for the following problem : You can see windows, desktop, etc. on TV, but DVD output doesn't display (with WinDVD, all I get is audio and the WinDVD logo showing up at startup). The solution is to define the TV output to be the primary output in the ATI settings. For that go in the "Properties" of the desktop background, then : Parameters -> Advanced... -> Displays -> enable the TV output, if not, and click on the check box, then should display TV as Primary, and Panel as Secondary output.

You can save this configuration in the "Model" at the top of that screen, and define a shortcut. Define another shortcut with the PC Panel being the Primary output. Then you can easily switch from one mode to another.

NOW, you start WinDVD with the PC being the primary output, and only then you switch to TV as primary output. Miracle, the movie shows up on your TV. Then you can switch back. But if you start WinDVD with TV as primary output, it will tell you that it can't recover, and you'll have to stop it.