Oh, they've got the DVI on the SDVO. You sure that thing can't run as PCIe, too? That was one of the whole points of the SDVO spec. I could see HP being cheapskates and not making that possible, though.
Regarding making the onboard video run at TV timings, find the "Soft15kHz" thread. There's other ways to do it, but that's a popular one. The idea is that you make the VGA output run at a TV-compatible resolution (480i or 240p). It won't work with a PC monitor at this point, but you can use an RGB to S-Video converter (tons of options available) to hook it up to your TV using S-Video. The results are usually pretty decent, though it depends on the quality of your TV.