How dumb is too dumb?

I stumbled on this article on Monday: How dumb is too dumb to operate a computer?

After years of being a geek, I have often thought that operating a computer should require some sort of license, much like operating a car. While the effects of poor operation are not as obvious, in today's interconnected world one user's poor computer skills really do bring down the neighborhood.

Typically, the most attacked ports on the Internet are being attacked by computers whose primary operators are unaware that their computers are participating in any sort of attack.

I guess it might be like allowing all sorts of people to buy guns, to defend their homes (of course) and having other people come in and borrow those guns, without their knowlege, who in turn shoot up the neighborhood.