All antivirus tools are not perfect, they miss things or can be purposefully damaged. Here are some free tools that help you supercharge your AV utility and keep your Windows computer clean.
BitDefender Online Scanner is a web application (requires Internet Explorer) that scans your system’s memory and all files, detecting and removing infections. Perfect to check if you regular antivirus app missed a malware infection.
also I recommend ThreatFire Free. ThreatFire is a free download that supplements (now don’t go deleting your AV engine just yet) your regular antivirus program. It’s cool because it has “behavioral-analysis protection” that basically attempts to identify Trojan horses and other malware based on how your PC operates. Those with “slowing” computer may want to check this out!