Vista MCE DVD S/PDIF audio output

I am running Vista MCE on my machine and have setup to output standard analog speaker to connect directly to TV input? I am using Nvidia Purevideo and set the DVD playback to S/PDIF audio outputs but it was not working. I have to go back to Vista MCE audio setting to set it S/PDIF audio outputs and then it started working. The issue is that I dont want to turn on the AMP all the time for the standard TV playing. It will not like Vista MCE allow audio to output to multiple output. How can I only setup Vista MCE to send DVD playback to S/PDIF audio outputs? Thanks for any help.

I think that you should not use the Nvidia's decoder with Windows Vista, since it is not fully compatible with Vista Media Center decoder.

Yeah, I have removed the Nvidia's decoder and get back to microsoft vista's default decoder but I do not know how to set the DVD to play via s/pdif digital output and leave the rest of the audio to the default regular analog output.