by , 11:50 AM EDT, September 19th, 2008

Microsoft launched its third in a series of special ads to spruce up the image of Windows on Thursday night. The ad features a selection of cameos, some famous and some not, showing that Windows is used by all kinds of people. The ad opens with a comment by a John Hodgman lookalike, Microsoft employee Sean Siler, that PC users have been stereotyped.

The ad shows many different kinds of people who do lots of different things for a living. The one thing they all have in common is that they don't look like John Hodgman and don't act like him, thus trying to lift the stereotype.

The ad also raises the question whether there ever was a stereotype of PC users and whether that was the point of the Apple "Get a Mac" ads -- because John Hodgman portrays a computer, not a person.

"I'm a PC"

The campaign, which is now taking a different direction after a generally negative response to the first two ads with Jerry Seinfeld and Bill Gates, never mentions Vista, but it does try to reinforce the idea that a lot of smart, interesting and diverse people use Windows PCs in productive ways.

Yesterday, a New York Ad executive doubted whether the defensive approach, casting Microsoft as the stereotyped victim, will be effective with customers.

The ad has also been posted at YouTube.