Independent test organization AV-Comparatives has tested 20 Anti-Virus products in an on-demand test in February 2010.
G Data scored highest in this test, with a detection rate of 99.6%. See http://www.av-comparatives.org/images/stories/test/ondret/avc_report25.pdf for the full test report.
AV-Comparatives commented: “Percentages refer to the used test-set only. Even if it is just a subset of malware, due its size, it is important to look at the number of missed malware. For example, 0.3% means almost 3700 missed malware samples from the used test-set.”
This is in line with our experiences. Even the best Anti-Virus program is not protecting you 100%. Users should use second opinion scanner regularly, just to be sure.