Microsoft CEO Steve Ballmer speaks at a special media event to announce the next generation Windows Phone, Windows Phone 8, at the Bill Graham Auditorium in San Francisco, the United States, on Oct. 29, 2012 (Xinhua/Li Mi)

　　Microsoft CEO Steve Ballmer speaks at a special media event to announce the next generation Windows Phone, Windows Phone 8, at the Bill Graham Auditorium in San Francisco, the United States, on Oct. 29, 2012 (Xinhua/Li Mi)

　　Microsoft CEO Steve Ballmer speaks at a special media event to announce the next generation Windows Phone, Windows Phone 8, at the Bill Graham Auditorium in San Francisco, the United States, on Oct. 29, 2012 (Xinhua/Li Mi)