Is there a svideo socket or composite video socket on the back of your Radeon? If so then wire that to your TV or AV amp. Then then run the line out from your soundcard to the amp.

Not sure about the default drivers that comes with Windows but if you download the ATI drivers then you should be able to tell it to output to the TV. You may need to set the TV output as the primary display and the monitor as the secondary display.

Any PC DVD player software should be fine.

- Trevor