Here's how to make a computer 100% secure:It made me think of Marcus Ranum's classic Ultimate Firewall, now updated to include Intrusion Prevention and Deep Packet Inspection Application Security.
Don't connect it to the Internet.
Don't turn it on. No...come to think of it, that doesn't work. Don't plug it in.
That's some security, right there.
If you are interested in security, or want the distilled security wisdom of the ages, this is a good place to start. Painless, too.