DefencePlus enables you to protect your system from hackers who use buffer overflow security flaws in Windows to infiltrate and take control of your computer. With DefencePlus, you will no longer fear that some unscrupulous parasite will gain access to your documents, passwords, and credit card numbers. It is continuously watching for worms like Blaster or Sasser and stops them from the outset before they compromise the integrity of your system.

avast! Virus Cleaner is a free tool that will completely remove selected viruses from PC.
It is able to stop viruses that are active in memory, it will disinfect your files, remove virus registry & startup items, and virus working files.
Currently, it can handle these virus families: Badtrans, Beagle, Blaster, BugBear, Ganda, Klez, MiMail, MyDoom, Nachi, NetSky, Nimda, Opas, Parite, Sasser,Scold, Sircam, Sober, Sobig, Swen, Yaha,Zafi incl. var.

Detects and removes many worms, trojans and backdoors: Mytob, Mydoom, Beagle, Netsky, Sasser, Blaster Zafi, Startpage
Switches
/G - Don't check the AVK Monitor status (optional)
/N - Scan mapped network drives (optional)
/I - Do NOT remove Internet temporary files and Cookies (optional)
/D - Delete specified file, path required (optional)

More info: http://wirusy.antivirenkit.pl/