I've had a hard time getting the TV-out working on my PVR-350. I've tried some things I found in this forum to no avail. So I figured, heck, I'll made sure the card works. So I installed Windows 2000 and the Hauppauge WinTV app. The TV out works. But here is what I don't understand. The TV out on the card only shows TV. Nothing from the computer gets shown.

So my question is, can I expect this if I get it working in Knoppmyth? I would like to be able to see the Knoppmyth menu, Onscreen display, etc. through the TV-out.

Yes, KM is smarter than MS-Windows on this count. It uses a framebuffer driver to do it. If you use the 350 setup script it should take care of most of the details.