Although the freeware "McAfee Labs Stinger" provides no comprehensive virus protection, but it is quite useful if the computer is already infected.
McAfee Labs Stinger: Malware second scanner
The handling of freeware is very easy."McAfee Labs Stinger" starts without installation right after a double-click the downloaded EXE file. Now start the scanning process by clicking on the button "Scan Now". Are viruses & worms tracked, these adjusted immediately whenever possible.