Millions of computers worldwide have already been infected with the Conficker worm.
So far, it hasn't done any major damage, but it is replicating itself. And on Wednesday, it's apparently programmed to "phone home," possibly getting instructions from some master computer to start causing real problems.
Most experts don't expect anything dramatic on Wednesday, but Windows users are being advised to make sure to apply the latest Microsoft security patch and to be sure they're using up-to-date antivirus software. In this podcast, I discuss the worm with David Perry, education director of Internet security company Trend Micro.