You might have seen headlines about cyber attacks on US government and South Korean websites. The attacks made the front page of the Wall St Journal today, so it isn't just a few system managers whining about spam. Attack traffic is so heavy that my internet access has slowed perceptibly.
Microsoft Windows is the root cause of these attacks. Windows is like swiss cheese, security holes everywhere. Attackers break into Windows computers thru these holes, and install robot code ('bot for short) which upon command fires off an endless string of requests to the victim computer demanding transmission of the website's first page. Each 'bot can fire off hundreds of requests per second. 'Bot nets of hundreds of thousands of captured Windows machines can overwhelm anything on the internet. Right now it's a major nuisance. But in the future when all bills are paid, all messsages go, all news comes from blogs, all music is downloaded over the internet, this kind of cyber attack will hurt more.
The only fix is to get on Microsoft's case and demand a secure Windows. It is perfectly doable. Microsoft doesn't fix the problem 'cause they don't see any money in security.