What's impressed me the most about my home theater PC experience is the fact that, apart from swapping out the motherboard thanks to a busted capacitor, I haven't had to touch the system. It's running on relatively modest hardware—a 2.4GHz Pentium 4 processor, 512MB of memory, GeForce FX 5600 graphics, generic DVD burner, 250GB Hitachi SATA drive, WinTV PVR-250 tuner, and a cheap Envy24PT-based audio card—and it's been rock solid for years running 24/7. In fact, the system has been so stable that I'm a little scared to mess with it. An Audigy2 has been sitting on the shelf for a couple of months now just waiting to grant the system DVD-Audio support, but I'm hesitant to upset the delicate balance that has kept the rig so reliable for years.
Of course, I'm going to have to upgrade eventually. HDTV beckons, and sooner or later, I'll start all over with dual tuners and more horsepower. There are some things that won't be changing, though. ATI's Remote Wonder is a godsend, and it'll follow me wherever my home theater PC travels take me. The remote's programmable nature makes it easy to adapt to different applications, and I can't live without the Winamp plugin. In fact, I can't live without Winamp. The interface all but requires a high definition TV, but the visualization plugins make it all worthwhile regardless of whether you're stone cold sober or in an intoxicated trance.
I'll probably stick with Zalman's passive water cooling setup, too. It's been leak-free and whisper quiet for years, and that's gone a long way towards warming me to the idea of water flowing around inside a PC. Of course, passive water cooling isn't the most economical path to quiet computing, but in my experience, it's easily the most silent. Once you've experienced near silence in the living room, it's hard to live with even marginally higher noise levels.
That, and the Reserator's giant blue phallus of a radiator tower makes one heck of a conversation piece.
Suffice to say that I'm completely sold on the home theater PC concept. I've played with TiVo and various set top DVRs, but the flexibility of a fully functional PC is hard to beat, especially when you don't need particularly extravagant hardware. Home theater PCs need not be complicated for more casual users, either. I built up a box for my parents a while back and I'm not sure they even watch live TV anymore. In fact, they use the system so much that they're already considering expanding its hard drive capacity beyond the existing 500GB. If that isn't a testament to the glorious potential of a home theater PC, I don't know what is.