Most basic, low power home surveillance system [closed]

"Infrared motion detectors are cheap and widely available for $10 or less. You can probably find one pretty easily with adjustable sensitivity that controls a switched device of some kind. Just hook those wires into anything that can activate your computer. You can configure your software to activate whenever the computer wakes up, check the webcam for motion, and take whatever action you're imagining.

Here's one short guide I found on tapping into the electromechanical relay on a cheap motion detector: Motion Sensor Switched Output Hack. You could also construct a simple circuit from a more barebones IR sensor, but it might not be worth the effort when the relay ones are so cheap.

If your motion sensor already has a relay on it then even a software guy such as yourself on shouldn't have trouble connecting it to your PC; it will function just like a switch. I've wired things directly into my computer's power switch before, but in this case it would make a whole lot more sense to attach it to a spare keyboard controller. Your netbook should be able to wake on a keypress, and you could easily monitor the signal from your program.

Though I do agree with NoCarrier's thought that the netbook's power consumption could be so low that if this sounds like a hassle then you might as well just leave it on."