mack - 11:07 am on Jun 12, 2013 (gmt 0)
I get those calls regularly, I don't even have a windows machine. From what I understand of this scam, they advise you there is a problem, obtain your email address over the phone and talk you into visiting a website. From there they can remotely access your machine. Not sure if they pretend to fix it, or install new payloads. Either way you need to pay with cc before they finish the job.
Someone I know fell for this. From what I can see all she git for her money (£45) was a tracking spyware toolbar on IE and an edit to the host file pointing all google searches to a 4th tier search engine.