Looking for a good PC-based automation

I have extra PC's sitting around and I'm looking for a way to use them with the home theater and possibly other home devices. I've read about x10, though I don't fully understand what that's all about. Anything else come recommended? I would like to control things like lights, A/V equipment, etc.

 

X10's been around quite a long time. I've used it for at least 15 years on and off (no pun intended) and it's worked well. However, I don't use my computer interface anymore. Instead, I got a wireless remote control, which means I can dim or turn lights on/off anywhere in the house. You CAN switch appliances with X10, using their special switch receptacles, but I don't recommend doing it with audio components. Some, like my CD changer, lose their programming when turned off completely. A lot of today's devices, too, don't turn off, they just go into a standby mode. And something like a power amplifier would probably create too much of a load on an X10 module.

That's just for starters...