"I occasionally watch DVD's on the PC and use the DVD player to provide sound, but use the built in DVD player on the PC to provide the picture"
LoL! (sorry) I just dont get it. Do u buy 2 disks to watch 1 movie? LMAo

All u need is any video card thats got a Video In. I have an old All in Wonder and can watch tv, playback from external sources as well as record. Ah, yes, u'll have to connect sound to the sound card.
Cheers