Microsoft's Windows Live OneCare came in dead last out of a group of 17 antivirus programs tested against hundreds of thousands of worms, viruses, Trojan horses and other malware, an Austrian antivirus researcher reported Wednesday.

The AV Comparatives Web site, which is maintained by Andreas Cleminti, posts quarterly results of tests that pit the top antivirus products against a dynamic list of nearly half a million individual pieces of malware.

Top dog, according to Cleminti's tests, was G Data Security's AntiVirusKit (AVK), which nailed 99.5 percent of the malicious code. Not far behind were AEC's TrustPort AV WS, at 99.4 percent, Avira's AntiVir PE Premium, at 98.9 percent, MicroWorld's eScan antivirus, at 97.9 percent, F-Secure's antivirus, at 97.9 percent, and Kaspersky Labs' AV, which stopped 97.9 percent of the malware.

Better known products such as Symantec's Norton antivirus and McAfee's VirusScan posted results of 96.8 percent and 91.6 percent, respectively.

Holding the bottom spot was Microsoft's Windows Live OneCare, the consumer security suite that the Redmond, Wash. developer launched last year. OneCare took care of just 82.4 percent of the malware.

Cleminti also tested the 17 products against polymorphic viruses, those which produce sometimes vast numbers of variants as they try to sneak by scanners. "The results of the polymorphic test are of importance because they how flexible an antivirus scan engine is and how good the detection quality of complex viruses is," said Cleminti in his write-up.

Only Symantec's Norton AntiVirus and ESET's NOD32 antivirus caught every variant of the 12 polymorphic families, he said. In that test, OneCare placed 15th, detecting every version of only two families, and missing seven of the polymorphic families completely.

Cleminti's report is available online (download PDF).

This is not the first evaluation to give a Microsoft security program a black eye. Last week, for example, Australian security company PC Tools released research that claimed Windows Defender -- Microsoft's anti-spyware title -- detected just 46 percent to 53 percent of spyware.

"We are looking closely at the methodology and results of the test to ensure that Windows Live OneCare performs better in future tests," a Microsoft spokesperson said.