Got my first call like that this afternoon.  Just hung up on him but your idea is better.

A person who speaks with a India accent stated that I have a virus on my computer. I knew right off that this was a scam, so I told him to wait a minute, and then left him on hold,until he hung up the phone. Do not get upset with these individuals get even. You put them on hold and after about 2 calls they will not call back.