Microsoft will never call you.

I have recently seen an uptick in the amount of people who are getting fake calls from (or false requests to call) Microsoft. Sometimes these calls are out of the blue and sometimes they manifest as a phone number that shows up on a scareware Web page, urging you to call immediately because your computer is supposedly infected.
The thing you should know is that Microsoft will never call you for any reason. If you had the most virus-infested computer in the state of Minnesota, it would be your ISP (e.g., Comcast or Centurylink) that might contact you, but even that is unlikely.
The point is to be very suspicious of these kinds of tactics, for they use social engineering. Social engineering is a type of hacking that involves capitalizing on human nature to infiltrate systems. In the case of these calls (usually coming from India and Bangladesh), the scammers are capitalizing on your trusting nature and desire to be a good steward of your technology.
What should you do if you get a call like this? Hang up or interrogate them and then hang up. You are probably no more likely to be infected because one of these scammers called you. Unless you let them take over your computer remotely, they have no idea as to whether your computer is infected or not.
This is a new, slimy business model in India, Bangladesh, and other countries in that region, where call centers prey upon Americans through the telephone.
If you want to feel safer after a call from a scammer, call a trusted tech guru and/or run a virus scan with Eset online scanner.
Stay safe out there.