Competitive zeal of Ballmer key element in Yahoo chase

Once, when Horwitz was one of about 650 employees in the company, Ballmer greeted him by name and told him he'd hit Horwitz's car in the parking lot a month earlier. Horwitz's old beater was undamaged, but Ballmer told him he had to shell out $1,500 to get his own car repaired.

Lots of things about Ballmer, 52, belie his outsized reputation and his outsized wealth of $15 billion, which makes him America's 16th-richest person, according to Forbes magazine.

He has lived with his family in the same suburban house for years. Like many CEOs, he has 13-hour days glad-handling customers. But unlike many of his workaholic counterparts, he gets back home often and boasts he gets seven or eight hours of sleep a night.

Ballmer grew up in the Detroit area, where his father was a manager at Ford Motor Co. At Harvard, where he was equipment manager for the football team, Ballmer lived in the same residence hall as Gates, who famously dropped out to launch Microsoft in 1975 with Paul Allen.

After Ballmer graduated with a degree in mathematics and economics, he got his first job at Procter & Gamble Co., handling marketing for Duncan Hines' Moist & Easy cake mix. His cubicle mate was Jeffrey Immelt, today's CEO of General Electric Co.

Gates lured him to Microsoft from Stanford business school in 1980, giving him broad management responsibility. Ballmer was known for being funny yet intimidating. He would learn details about the company by immersing himself in certain aspects of the business, whether it was by living in Europe for a few months or acting as Phoenix-area sales manager for a while.

Ballmer was given the title of president in 1998, as Microsoft was fighting off the Clinton administration's attempts to break up the company. Ballmer became CEO in 2000, while Gates held onto the board chairman's seat and created a new title of chief software architect for himself.

As Microsoft grew into a dominant force in computing, thanks to the mass popularization of its Windows operating system and Office software, Ballmer and Gates were close.

Ballmer was best man at Gates' wedding.

They also have been unafraid to confront each other, shouting if necessary. One story holds that in 1985 Gates threatened to fire Ballmer if Windows wasn't on the shelves by the end of the year. It was ready by November.