Microsoft Malicious Software Removal Tool
If you updated your Windows XP, 2000, or Server 2003 product within the last week, you might have noticed the addition of the Malicious Software Removal Tool that Microsoft is now providing. This software should find and remove specific malicious software, specifically Berbew, Blaster, Gaobot, DoomJuice, Mydoom, Nachi, Sasser, Zindos.
If you download it via Windows Update, it runs in the background and then deletes itself. If you download the tool yourself, you can run it yourself whenever you wish.
Windows Update should release an updated version of this tool every second Tuesday of the month.