The Conficker worm—as in an online worm,  a type of virus that lives unnoticed in your PC while spreading itself to others over the Internet—has been one of the hottest online-security stories over the past few months. The worm started infecting systems big-time last fall. But the biggest chapter in this story might be yet to come.

Up to now, Conficker, which affects only Windows computers, has clogged networks and infected an estimated 12 million computers. It's also been able to shut down antivirus and other security software. "But it hasn't implemented a nasty functionality, yet," says Ed Skoudis, co-founder of IntelGuardians.

However, experts fear it may, come April 1. There's plenty of speculation about what exactly could happen on April Fool’s Day, the day Conficker is programmed to connect to other PCs forming a “botnet”, but no one knows for sure. So you'll want to take whatever steps you can to protect yourself.

That means ensuring your security-software subscription is current and checking that updates are being implemented. You should also run Windows Update—look for that or Microsoft Update on your Programs menu—to get the latest critical patches and the malicious software removal tool which will kill Conficker. Finally, this is a great time to make sure your data is fully backed up, using one of the several available options.

For more on staying safe online, take a look at our Online Security Guide for more tips. — Donna Tapellini