It’s a Microsoft site which will tell you you’re secure if you’re using Microsoft.
A little more scepticism might be appropriate on a security forum: I mean, if people are this naive here, do any of us know what we’re talking about?
The MS security product in question is SmartScreen which has a huge false positive rate.
http://dontsurfinthenude.blogspot.com/2011/08/microsofts-bad-reputations.html
If avast! had that sort of false positive rate, there’d be howls of protest, yet for the Microsoft fans, it’s fine.