I'd say the best bet is to get a monitored system if you live in a bigger area, however if you wanted to go the camera thing, I'd say one of the best cheapest places to order from is X10, they have some really nice packages, ones that'll even call designated phone numbers if it's set off, here's their site (it's not the neatest looking site)
http://www.x10.com/
They even have a dog barking alarm which might be handy -
http://www.x10.com/products/x10_dk9000.htm
I myself have a nice 100 pound Pit Bull/Sheppard which keeps my place safe, but I sometimes worry when we're gone out of town and he's at the kennel.