Microsoft’s Malicious Sofware Removal Tool
Microsoft’s Windows Malicious Software Removal Tool checks Windows XP/2000/2003 computers for infections by malicious software such as Blaster, Mydoom, and Sasser, and then aids in removing malicious software. The tool also gives you a report of the outcome after the detection and removal process is complete.
You can run this tool either by manually downloading it from Microsoft, or run it right from Malicious Software Removal Tool page. Windows XP and Windows Server 2003 SP1 users can also get the latest version of this tool from Windows Update.
Microsoft releases an updated version of this tool on the second Tuesday of each month. New versions are available through Malicious Software Removal Tool page, Windows Update, and the Microsoft Download Center. This tool is not a replacement for anti-virus software so make sure you are keeping your virus definition files up to date.