Just to give people an idea of the seriousness of the past few worms, I offer this bit from my home security report on it:

31730 total attacks, 3015 unique hosts
169 CodeRed Version 1 attacks
6920 CodeRed Version 2 attacks
0 CodeRed Version Unknown attacks
24641 Nimda attacks (Roughly 1449 every hour, or 24 a minute)

all on one little IP...