"If you take a normal Windows PC and connect to the Internet, you
  will be infected in 10 minutes (without protection)," Mikko Hypponen,
  Anti-Virus research director at Finnish data security firm F-Secure
  (FSC1V.HE), told Reuters.

(This is more directed at companies—especially large ones like
mine—than consumers):

At some point, you have to stop blaming Microsoft and blame the people who
keep buying their products. How many more times will it take? How much more
lost money?

Update: The
weapons industry
has been dealing with the issue of who to blame for
quite some time—with a mixed set of results. Maybe there should be a
mandatory background
check and waiting period
for all Windows purchases?