Those systems are awesome, the cameras help out a lot for protection, especially if you have GOOD cameras. My father does this for a living, he has his own company, the works. The system he has at his house is CRAZY!
He has 16 cams 8 of them hi def. and all with NV. The DVR is windows based and records up to 2 weeks with 3 160Gig HD's. Yeah its crazy, and its not a bad neighborhood, its just he wants to see EVERYTHING.
Thats a nice system though, something on the likes of what i would put on my house. Nice work!