Conficker is thought to have infected more than 10 million PCs worldwide, and researchers estimate that several million of these machines remain infected. If the criminals who created the network wanted to, they could use this network to launch a very powerful distributed denial of service (DDOS) attack against other computers on the Internet.

April 1 is the day that the worm is set to change the way it updates itself, moving to a system that is much harder to combat, but most security experts say that this will have little effect on most computer users' lives.

Nevertheless, many people are worried, according to Richard Howard, director of iDefense Security Intelligence. "We have been walking customers down from the ledge all day," he said. Often, the problem has been that company executives have read reports of some April 1st incident and then proceed to "get their IT and security staffs spun up," Howard said in an e-mail interview.

That hype will probably intensify when the U.S. TV newsmagazine 60 Minutes airs a report Sunday on Conficker, entitled "The Internet is Infected."

Conficker "could be triggered, maybe on April 1st ... but no one knows whether on April 1st they'll just issue an instruction that says 'Just continue sitting there' or whether it will start stealing our money or creating a spam attack," CBS reporter Lesley Stahl said in a ahead of the show. "The truth is, nobody knows what it's doing there."