Some anti-virus programs are better than others, but we've found that most cannot protect the computer from everything.  The best thing to do is to stay away from certain websites, and enhance the protection of your computer with an anti-Malware / anti-Spyware program in addition to the anti-Virus software.

1USA recommends SUPERAntiSpyware software -- it really IS super.
SAS works along with all brands of anti-virus software except Kaspersky and Avast version 5.
Check out the features of SAS:

 SUPERAntiSpyware is the most thorough scanner on the market. Multi-Dimensional Scanning and Process Interrogation Technology will detect spyware other products miss!
Easily remove pests such as Vundo, TDSS, AntiVirus Pro 2010, and thousands more!
Repair broken Internet Connections, Desktops, Registry Editing and more with the unique Repair System.   Provides daily definition updates.  Over 20 million users worldwide.

More Details at www.SUPERAntiSpyware.Com
The Free version is good for periodic manual scanning - but may be too late to prevent new infections.
The Professional version as the ability to prevent new infections as they occurr.
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