"The summer saw a surge in the number of hijacked home PCs or "zombies", say security experts.

The Shadowserver Foundation, which tracks zombie numbers, said it had seen at least a threefold increase in the last three months.

More than 450,000 computers are now part of zombie networks, or botnets, run by hi-tech criminals, it said.

The rise is believed to be linked to attacks that booby-trap websites to try to infect the machines of visitors."

http://news.bbc.co.uk/2/hi/technology/7596676.stm