Thanks!! That was really helpful.
I guess I will be running the Arduino Mega with an ethernet shield.
The website will be fairly simple, and I am not too worried about the security since it's not going to be "online" per say, it's just in the network, so you'll have to be on the network to control the house.
Maybe once I get that working then I'll take it online and see if I can remotely control my house :-P.
I will be using 5v relay so I can use the same power supply as the Arduino, or 12v relay, one or the other. 12v would probably be easier since I can just attach it to a car battery and have that on a float charger so that I'll always have power even during power outage. The system will be controlling solenoids to lock and unlock doors as well, so I would appreciate the back up power.
Does anyone know if CAT5 cable can carry 12v power? and what the limitation would be? or 5V? Because I am replacing all the switches with relays and push buttons, which will be plugged into the Arduino.
My workblog will be here:
http://vinhworkblog.blogspot.com/