Here's an interesting article in Wired today:
http://www.wired.com/news/infostruct...,56902,00.html

But the market research firm also expects a coordinated terrorist attack that will bring the Internet "down to its knees for a day or two" as retaliation against the United States if it goes to war with Iraq.

....

A "cyber-terrorism event" will take out the Internet

IDC fears that a war with Iraq will galvanize hackers to use their skills, perhaps in a coordinated way, to create "economic disruptions" through denial-of-service attacks and even physical attacks on key networks. IDC went as far as to say that such an attack would bring the Internet "down to its knees" for a day or two.