How do I make my old computer into a home security system with cameras?

I have this old computer lying around and I want to install some cameras into my home. What do I need to make this work?
For example, what software and other necessary stuff do I need for my computer?
Also, I don’t want to spend a lot of money on this, so cheap tips please.

Thanks

This is a complex answer that would be too long to answer here, but I can point you to a few useful pages that can give you step-by-step instructions on how to do this:

http://www.engadget.com/2005/02/22/how-to-turn-your-laptop-into-a-home-security-system

http://archives.chicagotribune.com/2008/jun/17/news/chi-diy-surveillance-0617-digitajun17

http://www.ugolog.com/pages/25-applications-to-turn-your-webcam-into-home-security-system

Hope it helps!
–Fabrice

Homeland Security 4 Camera Security System

16-CH H.264 DVR 1TB HD 8 Dome and 8 Gun Camera Security System $1157.64 Keep your property safe and secure with this 16-channel security system. H.264 compression allows you to maximize your hard drive recording time, and delivers good digital video quality when viewing over the Internet or 3G mobile networks.