Microsoft's Free Antivirus Software Actually Works! Program performs well in stress test By Kevin Spak, Newser Staff Posted Oct 1, 2009 1:00 PM CDT 22 comments Comments Microsoft Security Essentials is actually pretty good, tests show. (Shutterstock) (Newser) – Want a great, free antivirus program from a big software brand? OK, it’s from Microsoft, and … wait! Come back! Believe it or not, Microsoft’s new Security Essentials software is pretty darn good. AV-Test.org ran it through a bevy of tests and found the freebie performed admirably. In its first outing, it nabbed all 3,700 viruses, Trojans, and worms that testers threw at it. Then they loosed it on a computer already infected with 545,344 malware samples, and it scrubbed 98.4% of them. It’s relatively efficient, too. A full scan took a whopping 8 hours in a Boston Globe test, but used so little CPU that the system ran smoothly in the meantime. It’s not perfect: It can’t detect unknown menaces, and sometimes leaves benign bits of malware behind. But it’s pretty great for the price.