There is a guy in Apex that has this in his house, Robertmee is his name on here. I think he did the install himself also. Send him a PM and see what he says.
Hey, don't be giving away all my secrets
Yes, I have an 8 channel DVR card that I slapped into one of many used PC's I come across. The card handles all the video processing, so any old PIII PC is sufficient. Throw in a big HD and you have a relatively inexpensive CCTV setup. I used a Geovision card. You have to be careful with multi-channel cards and read the specs carefully. For good motion capture you really need in the 6 to 10 FPS (frames per second) record rate. The problem is that many of the inexpensive DVRs advertise 25 FPS but that's across all channels. So if you are recording 8 cameras, you get an effective record rate of 3 FPS which gives choppy video. The Geovision software has all the bells and whistles, and offers various remote server options (TCP, web, jpeg, e-mail alerts, et al). For viewing, I have the camera feeds paralleled into my video distribution so I can see any camera on any TV. I also have some inexpensive touchscreens around that show a matrix display of all the cameras with a blown up view of any camera recording motion.
As for the cameras, I used some B&W w/ IR and audio built in. They were $40 bucks a pop and give 480 lines of resolution. Any less rez, and you can't discern faces, etc. The IR is okay for facial recognition at a door, but won't do much beyond about 5 to 8'. BUT, that could be supplemented w/ additional IR blasters. The nice feature on the cams I chose is that they used a single 8 conductor cable to transmit power, video, audio, IR and motion detection. So, with a single Cat5 cable, it made installation a snap. Some of the other cameras use RG59 coax and require a separate 18/2 power feed. You can get coax/18/2 combo cabled (often called siamese). Others use proprietary cables (like the costco systems) that can make pulling the cable through walls/ceilings a pain.
One caveat....I designed and installed my system about 7 years ago. In that time, I've had one camera failure. BUT, as with anything electronic, there have likely been great leaps and bounds in technology and my setup may no longer be a viable option out of the box. If I were building a new house and doing it again, I might consider some of the Panasonic PoE cameras. These are powered over Ethernet. A single Cat5 cable and the data is streamed across your normal TCP/IP network. These also offer remote pan/tilt features and of course remote internet connectivity. Not sure what the centralized DVR options are with them, but I imagine there's stuff available.