I had just finished setting it up when I read this post. Here's how I did it:
I'm using a PVR150 with DirecTV on the S-Video input, and an old school sony web cam on the Composite input. Alt S into setup, create a video source using just the name, ie: Video Camera, and choose nothing else. Click finish, then escape, choose Input Connections and then select the composite input. For video source, choose Video Camera (or whatever you named your video source when you created it). Now click scan for channels. When it finishes it should populate the starting channel at channel #1 (mine did anyway, and it makes sense). Click finish, then escape, and escape again to exit setup.
Now to see the video, select Watch TV and hit 'C' on your keyboard to cycle thru the inputs on the card. I've got it set up on top of the TV for now and it works great, the kids get a kick out of watching themselves.
As far as sound goes, I have just the one input from DirecTV, so we actually hear the TV while watching the camera, but that's no biggie to fix. Not quite sure what I'm going to do with it, was just sort of playing around as I ran across it in a box of old computer junk. I hope this helps, my first post and all
