The fast-moving Conficker computer worm, a scourge of the Internet that has infected at least 3 million PCs, is set to spring to life in a new way on Wednesday — April Fools’ Day.

That’s when many of the poisoned machines will get more aggressive about “phoning home” to the worm’s creators over the Internet. When that happens, the bad guys behind the worm will be able to trigger the program to send spam, spread more infections, clog networks with traffic, or try and bring down Web sites.

The Conficker outbreak illustrates the importance of keeping current with Internet security updates. Conficker moves from PC to PC by exploiting a vulnerability in Windows that Microsoft Corp. fixed in October. But many people haven’t applied the patch or are running pirated copies of Windows that don’t get the updates.

Mac users collectively LOL.