Secure or insecure network?

My Dad doesn’t want to install antivirus/firewalls on any of the Windows computers in the house.

He thinks we’re safe with just the ‘firewall’ on the router. He won’t even run Firefox on any of them. I run www.easygeek.org , so obviously I know better, but I need someone else with ‘professional’ expertise to prove that we need security software.

Right now, I’m stuck with a Vista machine (the harddrive doesn’t like linux, my OS of choice) so I set my Avast scanner to High.

Can someone convince him, short of infecting my network?

PS He is generally tech savvy, he’s just far too trusting of Microsoft. Therefore, I can’t load ‘fake viruses’ to scare him or install security software without him knowing.