Although this is a worthwile project, the main flaw of course is that you're relying on a PC being up and running 24/7. If you are running Windows, then that isn't possible

In the control industry, the direction taken has been embedded controllers that you can program and monitor via PC, but do not need the PC up and running to use once programmed.

There are some temperature controllers that have an embedded web server. You simply connect the controller to your network, then open a browser on your PC to the URL of the device and start manipulating setpoints and such. Many use RS232 or RS485 communications via your PC serial port.

Here is a standard controller that uses RS232 to set it up and display on your PC:
www.omega.com/ppt/pptsc.asp?ref=CNI_Series&Nav=temp03

Here is a controller that can be setup with a PC via Ethernet:
www.omega.com/toc_asp/frameset.html?book=Temperature&file=CNI16_Series

There are controllers that do ramp and soak, which means you can set a lower temp for the morning, then ramp up to your daytime temps (over as long a time as you want) then gradually ramp down to evening lower temps.

Here is such a controller, but uses a serial connection, not an Ethernet connection:
www.omega.com/ppt/pptsc.asp?ref=CN8201_CN8202&Nav=temp03

Here is another:
www.omega.com/ppt/pptsc.asp?ref=CN9600&Nav=temp03

See the prices of these units? Not bad, eh? Of course you must add the thermocouple probe and wire and software, so it does add up. Also, you need to hook it up to an SSR that they sell. So it isn't cheap persay, but will do alot of wattage. They do not dim lights, but are perfect for non-light-emitting heaters like RHPs, ceramic bulbs and heat pads.

For lighting, I am not sure. Using a low-cost PLC, you could likely program dimmer function using pulse-width modulation, but I am not sure how for A/C lights. However, Helix does it cheaply, so it isn't difficult.

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