Stan Spotts turned me on to the Xbox Media Center Extender Kit. This sucker will let you use an Xbox (up to five of them!) to watch video content recorded on a Media Center PC.
Now, I've avoided the Media Center PC until now. I rolled my own PVR at home; I started with a Happaugue PVR250 but abandoned it last year in favor of an ATI All-In-Wonder 8500 DV. I've been happy with that, but I really wanted a solution to play back what I'd captured on the TV in the family room. (My PVR system is a noisy beast with five hard drives and four fans; it lives one floor down from the TV. :-)
I'd looked at the Prismiq MediaPlayer, but it got enough bad consumer reviews that I wasn't gonna plunk down $250. There's the SoundBlaster Wireless Music widget, but that's the same price and only does audio.
XMCEK is exactly what I want. No new box in the living room. Only problem is, I have to buy a Media Center PC. I like playing with technology; I build my PCs from parts, and I like it that way. I like being able to burn honest-to-gosh DVDs from the video I capture using my homebrew PVR. And I don't want to pay the profit overhead implied by a fully packaged Media Center PC.
Sigh. Maybe I'll just keep waiting.