We hear a lot of a claims and counter-claims about how much viruses and worms cost the average business, but what about ISPs? Their bottomline is more directly impacted by this kind of thing. My ISP reminded me to keep my Windows installation up to date . . .
I recall in the summer of 2002, the NIMDA worm was consuming a lot of my bandwidth and server cycles: scale that up across a broadband infrastructure and take a guess at how much a Comcast or Qwest might have to absorb in unnecessary upgrades (to cover wasted bandwidth) or additional payroll to meet their SLAs. Such is the power of a monopoly, they have to eat those costs.