I need a website/ info for no-techie people on why they need anti-virus and firewalls.

[mcveigh]

I am going to be doing some subcontracting work for a client. I will mainly be installing anti-virus and firewalls for his clients.
I am currently making up a price list, I am going to charge a flat fee, not my normal hourly charge.

I need some simple explanation for non-geeks about why they need this stuff.
can anyone think of where I caould find somethign like that? I am hoping to keep it under 1 page.