CHICAGO - AUGUST 28:  A poster in the window of the Apple store on Michigan Avenue advertises the Snow Leopard operating system August 28, 2009 in Chicago, Illinois. Apple today began selling Snow Leopard, the sixth major update of the Macintosh operating system. Getty Images logo Getty Images 5 months ago

CHICAGO - AUGUST 28: A poster in the window of the Apple store on Michigan Avenue advertises the Snow Leopard operating system August 28, 2009 in Chicago, Illinois. Apple today began selling Snow Leopard, the sixth major update of the Macintosh operating system.