The Microsoft Malicious Software Removal Tool is an anti-malware utility that checks computers running Windows 10 Technical Preview, Windows 8 and Windows 8.1, Windows 7, Windows Vista, Windows XP*, Windows Server 2012 R2 and Windows Server 2012, Windows Server 2008, and Windows Server 2003 for infections by specific, prevalent malicious software—including Blaster, Sasser, and Mydoom—and helps remove malware and any other infections found.
http://www.microsoft.com/security/pc-security/malware-removal.aspx