Microsoft Security Essentials "no-cost" anti-malware service for consumers, achieved the VB100 award for the August 2010 Edition of Virus Bulletin. "VB100 award is a public test conducted by Virus Bulletin, a highly reputable testing organization, designed to measure the detection effectiveness and quality of antivirus products. The most important validation of AV quality comes from independent certification organizations like Virus Bulletin."
In order for a product to be awarded VB100 certification, it needs to detect 100% of WildList malware samples and mustn't have any false positives or incorrect detections on the Virus Bulletin clean file collection. According to VB, "Detection rates were strong as ever...with no problems in the WildList or clean sets, Microsoft earns another VB100 award with ease."