This scam has been around for awhile, and recently hit the news.
http://www.ftc.gov/opa/2012/10/pecon.shtm
The scammers will claim to be from microsoft or some other big computer tech support company. They try to trick you into giving them remote access to your computer. They will try to charge you hundreds of dollars to clean your computer of non existant viruses.
Good for you for hanging up on him! Supposedly the FTC is going after these scammers, but lets face it, they are all overseas and not a whole lot that they can do about it.