The Security Mentor

Worms and viruses often enslave the computers they infect, putting the computers under the control of the virus creator. Then the virus creator may rent the infected computers to spammers or other criminals. At last report, the going rate was five cents per machine per use, which tells you that infected machines are cheap and plentiful.

Infected machines are so cheap and plentiful that one new Internet worm starts by checking whether the machine it just found is worth infecting. The "Bobax" worm runs a test to see whether it's on a machine with a high-speed Internet connection before it "phones home" to tell its creator that's it's enslaved the machine.

Keep your antivirus software and system patches up to date, or your computer may not even be worth a nickel.