Well you're both wrong. A brand new Windows 2000 install was corrupted beyond repair after just 8 hours of doing absolutely nothing online. Accidently visiting a russian pr0n site, is one of the less evils you can do to your PC. Being ignorant about security is much more severe than all the Russian pr0n in the world.
Wrong am I?
I've never had a server go down after just 8 hours. I use a hardware firewall & a hosts file.
Personally my PC has never been infected with a virus, although I have had some adware (most recently from a freeware game with a silent background installer) because I dont browse randomly very often and I have a malliscious site-blocking hosts file for when I do, and I do not use P2P software.
Of all the virus' my friends and family have had that I have removed (and there's been quite a few) I have never once managed to remove the virus with an anti-virus tool. In the case of Norton I actually had to uninstall it in order to be able to remove a virus by hand.
With PC-Cillin I even identified a virus by hand after a virus check missed it and then checked the details online to make sure I had the correct virus database and engine and it still couldn't find the thing - and that was a very serious one that stole my sisters credit card details resulting in £10,000 of fraud.
The last virus I had on my own computer was back on the Amiga when a friend bought a PC and gave me his games collection.