Some lab tests analyze how well antivirus and security suite products recognize and eliminate static malware samples. Others evaluate behavioral detection techniques, and still others measure each product's ability to detect malware-hosting URLs.

The test is grueling, requiring researchers to challenge 20 or more antivirus products with brand new malicious URLs every day for months, making sure to keep them up to date. Over the course of the test, they hit each product with nearly 2,000 real-world samples. A product gets full credit if it either prevents the malware attack completely or removes all significant traces. If the malware compromises system security, naturally the product gets no credit.

What about cases where the product displays a notification asking the user what to do? In those cases, the researchers always choose Allow, OK, or the equivalent wrong choice. A product that prevents infestation despite the user's error gets full credit. One that allows system compromise if the user makes a mistake gets half credit.

Almost all of the 20 products tested scored 90 percent or better. Panda Free Antivirus managed an amazing 99.9 percent, and Bitdefender Internet Security came close with 99.8. Kaspersky Internet Security, Trend Micro Internet Security, Avast Pro Antivirus, and Tencent PC Manager managed 99.7 percent.