Benefit using this scanner is that you can scan your PC with a new engine or if you not sure that the existing antivirus protecting you from every threats.
With Comodo AV Scanner you can scan entire hard disk, individual partitions, USB drives or specific folders and files for finding threats.
The scanner requires the installation of a small browser plug-in (IE, Firefox, Opera and Netscape) and is a one time operation. On subsequent visits to the scanning page you will be able to run scans immediately.
However it only detects the threats, no option for deleting them, required Comodo security suite to remove threats.