John Gruber:

There's a line in The Usual Suspects where Kevin Spacey's character Verbal Kint says, "The greatest trick the devil ever pulled was convincing the world he didn’t exist."

The greatest trick Microsoft has gotten away with is convincing the public that the Wintel PC platform is open. I think the familiarity John talks about in his piece is the main reason (coupled with the just-a-year-old PC they have) my parents haven't switched.