There's also a version of this Insteon device without the software for just ~$50.00. This http://www.smarthome.com/2414s.html
is the serial version, but there is also an USB version. The advantage of the serial version is that you can connect it to a stand alone home automation controller.
Actually, a stand alone home automation controller like the M1EZ8 from http://www.elkproducts.com
servers you as a gateway to several important home automation devices. You would have what in Home automation is called an hybrid solution - a PC for control of high level functions and a controller for the security and low level functions.
The M1EZ8 has supervised hardwire analog and digital inputs, it has outputs for controlling relays, has support for wireless security sensors from the GE/ITI/Caddx series and also supports Insteon, X-10, Z-Wave and UPB. The list is capabilities is too long. The best thing is that it is U/L compliant as home alarm, is programmable and can monitor and do basic control of your lightning if your PC hangs (or power is out - since it has backup battery).
I'm planning on testing Pluto on a laptop that I have and see if I can develop a driver for the M1G serial interface (M1G is the big brother of the M1EZ8). If I get Pluto AND the interface to the M1 to work I would be buying the rest of the equipment to install the Core and Orbiters later in this year.