I'm thinking about setting up a security camera system using a computer as a sort of security camera DVR.

The nearby electronics store sells PCI card where you can hook up video cameras. The cheapest is $119.99 and you can hook up 1-4 cameras to it.

I want to have it so I can go on the internet and see/hear what's going on inside the house. If you've seen the news recently there was footage of some black dudes ransacking a woman's house and she had a hidden camera set up. She saw them in her house stealing her kid's Wii while at work and called 911 and the police caught the guys.

The store had some cameras set up but the nightvision cameras have crappy quality with lots of static/snow on the screen (like a weak signal on a TV that's using the antenna).

I have some old computers lying around and was wondering what kind of computing power I'd need to set it up as a security camera DVR.

Computers are:

1.8ghz Celeron 2x512mb PC2700 RAM

Sempron 3000+ 512mb RAM

Sempron 3500+ 512mb RAM

Athlon 64 3200+ 512mb RAM