Microsoft Security Essentials Released

Security Essentials successfully detected all of AV-Test's current wildlist samples, nearly 4,000 of them. In a test using over 500,000 samples of viruses, worms, Trojans, and other high-risk malware, the product detected 98.44 percent. It wasn't quite as effective in a separate test using about 14,000 adware and spyware samples, but it still detected 90.95 percent of them.

In AV-Test's analysis, Security Essentials successfully removed the active components of all detected malware but left behind significant amounts of non-executable malware traces. That's a better result than I measured - I found that Security Essentials left behind executable files for many of the samples. It also successfully removed all of their active rootkit samples but left several of mine running even after alleged cleanup.