While I'm not familiar with Lorex cameras specifically, (or, obviously, your particular installation) I'd have a look at ZoneMinder: http://www.zoneminder.com
. It seems to be the best thing going in Linux security camera software. I've used it a little, and it's easy to configure and use, at least with my setup. FWIW, I usually find a hardware DVR to be money well spent. You get a level of reliability that it's hard to match with a computer/capture card system, provided you choose a good one. Then again, if this in the home, it might not be worth it. Anyway, good luck!