The newer Axis cameras are able to store up to 30 days worth of motion activated video on a 64GB micro SD card, right into the camera. No DVR needed! http://www.axis.com

You can just plug these into power, and let them run. If there is a "problem", hook up a computer and download the video. Or you can run ethernet cable/wireless, and run them all to a central computer, and access what's stored in the camera, from that computer.