Home Management Software for the PC ?

Urgoll asks : "Is there any software/hardware availlable for Linux (preferably) or Windows to control your home environment? I'm takling about being able to control the home temperature , various lights, water heater, etc from your PC, and hopefully with a dial-in interface, so that you can control your house when away from home... Imagine... Coming back from a vacation, and calling your house form the airport to raise the temperature, so you won't freeze when going to bed!" Most people in the know would say *X10!*, but I figured that this was cool enough to run for the folks who AREN'T and wish to do something like this.