Along with the plethora of patches released Tuesday, Microsoft also revised its free Windows Malicious Software Removal Tool for the first time, and as promised earlier, automatically added it to Windows XP users' download lists when they accessed Windows Update. The tool, which debuted last month, has been enhanced so it now detects and deletes -- or tries to -- all instances of the Korgo, Netsky, Zafi, and Randex worm families. January's edition cleansed systems of eight different worm/virus families, including MyDoom, Nachi, Sasser, and MSBlast. This month's edition adds four to bring the total to 12. The additions of Netsky and Zafi are particularly important, since several anti-virus firms tagged the former as the worst worm of 2004, and a Zafi variant made up a third of all viruses spotted by Sophos as recently as December 2004.