I've never ran anti-virus on my system, and I don't use a firewall. Plus, I use IE for web browsing. So, I've configured stuff a little, but how come I've never gotten any of these viruses you speak of?
I have no idea what you guys are doing to break your systems, other than intentionally installing malware (or being tricked by exes that have folder icons or other silly stuff). I installed my current w2k installation in 2000, and it's still working. Nearly five year old installation, and stuff still works great. I can only conclude that either you guys have bad hardware, or the difference is in the user.
Oh, and regarding third party software. I suspect you guys mainly use non-GNU software too. Your web browser, your mail client, your chat clients, text editors, etc... They're all from outside of the GNU project, third party software.