my suggestion may be difficult for you to impliment if you've never used linux before, but it's probably the cheapest way you could do this. Buy some wireless webcams, and find an old computer (I'd recommend at least 512 MB RAM and a 20 GB hard drive or so). Install Linux (Ubuntu is easiest) and install the program Motion. You have to configure it through config files. It will record when it detects motion in the images coming from the cams, no hardware motion detector required. Set up a cron job to delete files older than a couple of weeks to keep the hard drive from filling up. It's possible to view it while you're not at home, although I haven't actually done that (I have however set up webcams with an old linux computer as a security system for my bedroom. I used cams I already had and an old laptop. Total cost: $0). If you're interested, you have the information you need to look into the specifics of setting everything up. edit: just going to add that using the program Motion is far easier than it looks at first. When you're first setting it up, you can probably ignore instructions about finding and installing drivers for the cameras. The operating system will probably already recognize your cameras.