Anti-virus software does nothing to stop a worm,

For the average home-user, anti-virus software is a must.

We knew about this vulnerability a month before the worm emerged, ... If companies knew to scan even their perimeter machines, they could easily have seen this vulnerability and applied this patch and not be affected. I think what we're going to see is a new awareness around this and, as a result, new emphasis on planned vulnerability scanning so they have a fixed process.

The sole goal is to get on a person's machine in very silent fashion, disable anti-virus software and then download its bigger brother.

The Norton Anti-Virus gateway was affected,

As every new breed of virus is conceived, created and released into the wild, another small change is made to the anti-virus software to combat the new threat.