Caller has phoned my elderly in-laws several times saying he's from Microsoft's Help Desk, asking my mother-in-law to turn on their computer so that he can "help her with their e-mail." She's told him that she doesn't know anything about the computer, but that they have a Mac, so nobody from their home would have called Microsoft for help in the first place. She's too polite to just hang up on him, so she argues with him instead (he didn't know he was getting a Brooklyn lady, apparently). At any rate, she doesn't need this aggravation.
This appears to be a scam to install malware on your machine. Since it's to be installed by the user it will have full control of the machine - you're giving it permission.
Unfortunatly some people will fall for it.
The scammer id'd themselves as 'people connect usa', it sounded like a calls center in India.