At one time, I was regularly installing MS Security Essentials on my own
and other people's computers - PC Magazine took a look at the current MS
Windows Defender:

http://www.pcmag.com/article2/0,2817,1926596,00.asp

Their conclusion - "This is not the protection you're looking for."

"Testing reveals that you'll be much, much better off installing
almost any other free antivirus utility."

They rate it 1 1/2 out of 5.

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