I just had a call from one of my customers who told me they were contacted by a company proporting to be acting on behalf of Microsoft and that their computer was infested with viruses and that they were instructed to help.
The caller made my customer do something in the DOS prompt, from what I gather it was just to do a dir listing to make it look as if those files were infected.
They then wanted him to download a remote access client from logmein and this is where he became suspicious and said he wouldn't do it.
They're using social engineering techniques to scare people and I can see a lot of vulnerable people being caught out by this.
Beware that this scam is out there and if you have friends or family who may not be completely technically savvy it may bite them.
Fact of the matter is, if it seems to good to be true then it is. And remember Google is your friend. If you are unsure of anything put some effort in and research the issue.