Microsoft's free anti-virus offering, Security Essentials, has been given a warm review by a respected independent testing house.

Andreas Marx of AV-Test.org said that the newly beta-ed software seemed “very good” in tests against a range of virus, bot and worm samples from the most recent WildList.

He continued in a statement: “All files were properly detected and treated by the product. That's good, as several other AV scanners are still not able to detect and kill all of these critters yet.

“We've quickly tested the product's anti-rootkit and system disinfection capabilities (when a malware is already installed and active on a system) with a few samples and found no reasons to complain.”

On the downside, Marx noted that the product – originally codenamed Morro – had no behaviour-based malware detection, relying solely on signature-based detection. While this technique works well for older malware, the time required to process signatures of new malware and then distribute to user's desktops is often outstripped by the speed at which new attacks are generated.

The beta download of Microsoft's latest software was capped at 75,000 testers, and was full within 24 hours. The tool was initially launched in US, Brazil, and Israel, although UK users were able to download through Microsoft Connect.