The AsRock Ion 330 might be an interesting candidate for a home-theater PC. Because it has a Dual-core Atom 330 running at 1.6Ghz, it might actually be fast enough to record TV shows in Windows Media Center. I can’t vouch for it because I have not tried it myself, but right now, it’s probably the only Nettop that has a chance to do it.
You can find this little box for $380. It has 2GB of RAM, 320GB of hard disk and an Nvidia 9400M GPU/chipset that will playback 1080p video. I wonder if the cooling is passive, but I bet that it is not. For more details, watch the AsRock video. If someone tries to record TV from MediaCenter, please let us know if it works well.