You may be interested (and disappointed) by a follow-up article from Fred Langa: [URL] Some highlights/excerpts: "I use Microsoft Security Essentials and the Windows 7 firewall to protect all of my PCs. In over a year of constant use, I’d never had any malware trouble. But that abruptly changed... In the past few months, readers reported encountering new malware that masquerades as a security tool — malware that disables or bypasses Microsoft Security Essentials. I’d been trying to track it down for weeks. And suddenly, there it was.  Given this unexpected opportunity, I took a deep breath and clicked OK, knowing full well that I was voluntarily giving the webpage permission to interact with my PC... [he repeatedly, and knowingly, allowed several stages of prompts, intentionally trying to infect his system.] Throughout this time, Microsoft Security Essentials was silent — a major disappointment. However, every few minutes the Windows Security Center would wave the flag...  and urge me to “Turn on Windows Security Center service (Important).”LizaMoon [the name of this malware] blocked attempts to restart the Security Center service and hid itself from MSE. To clean up the mess, I needed to use another tool, Malwarebytes Anti-Malware, which disabled and removed most of the malware... When I rebooted the newly cleaned PC, I ran MSE again, which discovered [still] more pieces... [In conclusion] I have to say I’m disappointed that Microsoft Security Essentials didn’t detect or prevent this infection. It should have, and I hope Microsoft patches MSE pronto... The lesson? Using security tools is no substitute for common sense. Malware like this is actually very easy to avoid, if you pay attention to what’s going up on your screen." EDIT:   The above is simply intended as a direct follow-up to the prior discussion, which cited Mr. Langa's  earlier  views on the subject matter.   It is NOT, however, meant to imply that any other free [or paid] antivirus often recommended in this forum (avast, avira) would necessarily have fared any better in such a "test" --- I simply don't know the answer to that.
The following is controversial, but comes from Woody Leonhard at Windows Secrets Newsletter. His opinions reflect mine, at least as far as Windows 7 protection goes: [URL] Some highlights: Paying for antivirus doesn't improve protection  You don't need to defrag your drives any more  Drop your old backup program and use Win7's  OpenOffice is not a slam-dunk replacement 
Don't Pay for Software You Don't Need