For those looking into protecting there shit. Here's what I've been using.
Cheap cameras: Harbor Freight Tools has them for about 30 bucks Get the Black and White not the color. I've had mine out working for about 3 years now and haven't lost one yet ( got 6 running )
There are plenty of DVR cards that you can buy on E-bay and what not. I've ran a few and some are better then others. The main thing you wanna look for is FPS or IPS. this will tell you how much the DVR will capture. The higher the number the more frames you will get per second.
Full Motion is 30 FPS. You can go as low as 15 FPS and not notice much of a difference. Anything less then that, don't bother. Cards will say things like 120FPS, that will be for all the cameras total. So if you take that 120 divide that by say 4 then you will have 30FPS on each camera Take 120 and divide it by 8 then you get 15FPS and so on.
Hard drive space that is used will depend on size, frame rate and how many cameras will be on it so it's hard to say how much space it will take up. I recommend that the computer be separate from your everyday system as it will slow it down big time.
The other option is to use a time lapse VCR these are easy to find and for cheap. unless you have a multiplexor you will only get one channel or recording.
Multiplexor. Usually in 4, or 9 channels this allows you to see and record all channels onto one source.
Lastly when using B&W cameras look into Infrared lighting, Also cheap to get on E-bay and what not these will allow you to see in the dark. They only work on black and white cameras not color. Very nice to have if the lighting sucks where you want to record.