A great deal of good info on this thread. Hardening doors advice is top notch. Washington State has had a rash of "home invasions" lately. Some of them have been pretty rough. Some of them tho, have picked on armed citizens and have come out on the short end. When the Manse is undefended by you, other measures must be used. Fortifying is a good start, as is landscaping to protect the windows. Alarms and cameras seem a bit "after the fact". The motion actuated outside lights can be hooked to a radio. Break the beam, the radio goes of giving the impression someone is home. I have the "two dog alarm". They are small and very protective. I have experienced situations where BGs target a house and start by poisoning the dog. Outside food dish may not be a real good idea.
I live in a city park and the world walks by my house. I use something like this in my rear area perimeter. They can be used almost anywhere. Windows, doors, gates.
www.americanspecialityammo.com/Gadgets.html
You can load them with pepper spray, blanks, or whatever. Someone suggested using Claymores?? No, I would not recommend a Claymore