Those keynotes sometimes get a little rowdy–well, just a little. A highlight of Gates’ opening speech at the Consumer Electronics Show in January was some hand-to-Xbox combat with fellow Microsoft exec Steve Ballmer. The two sparred via the “Fight Night Round 3” video game, with Gates playing as Muhammad Ali and Ballmer as Joe Frazier. The bout went to Gates in a knockout.

Believe it or not, there was a day when Microsoft wasn’t a dominant force in the computing industry and the global economy. In 1985, a year before its stock market debut, it was still a scrappy start-up trying to ride a deal with IBM to bigger and better things–and software, like the Windows operating system, still came on floppy disks.

One of Gates’ goals in his slow transition from leading Microsoft is to devote more time to the Bill & Melinda Gates Foundation. In March 2005, Britain’s Queen Elizabeth II recognized Gates for his charitable works in Commonwealth countries and conferred on him an honorary knighthood. Gates’ wife, Melinda, is at right.

Gates is no stranger to the upper echelons of global politics. At the World Economic Forum in January 2005, he shared the stage with political leaders prior to a session called “The G-8 and Africa: Rhetoric or action?” (From left: Former U.S. President Bill Clinton, Gates, South African President Thabo Mbeki, British Prime Minister Tony Blair, U2 lead singer Bono and Nigerian President Olusegun Obasanjo.)

More recently, Gates hosted Chinese president Hu Jintao (left, with Ballmer, center) for a formal dinner and a tour of Microsoft’s campus. The April 2006 stop in Redmond, Wash., was Hu’s first landing on a trip that would eventually take him to Washington, D.C., to meet President Bush.

Their day jobs are vastly different, but Gates and Bono (left, seen here in a photo from February 2002) have a shared interest in charitable work in the developing world. Their good deeds led Time magazine to name the two, along with Melinda Gates, as its Persons of the Year for 2005. Bono has also stayed at the Gates’ mansion when U2 performed in nearby Seattle.

The celebrity schmoozing takes in musicians of all genres, including hip-hop artist Jay-Z (seen here, in May 2006) and former boy band notable Justin Timberlake.

But it’s as a hard-nosed businessman, not a socialite, that Gates made his name–and spent a considerable amount of time addressing charges of antitrust violations. Here, in a photo from March 1998, he appeared before a Senate Judiciary Committee hearing on market power and structural change in the software industry, along with fellow high-tech execs Scott McNealy (center, CEO of Sun Microsystems) and Jim Barksdale (right, CEO of the soon-to-be-defunct Netscape Communications).

On the antitrust front, the U.S. Justice Department settled with Microsoft, the European Union imposed a monumental fine, and some companies reached individual deals. Here, Gates and RealNetworks CEO Rob Glaser shake hands in Seattle in October 2005 to put an end to their long-running antitrust dispute, at a cost to Microsoft of $460 million in cash.

In a flashback to the early days of Microsoft and personal computing, Gates’ keynote at CES 2006 featured a video with a youthful Bill Gates and Microsoft co-founder Paul Allen.

A very young Bill Gates seems unphased in this 1977 mug shot taken by the Albuquerque, N.M., police, who had arrested the man-who-would-be-software-potentate for a traffic violation.

Building software and solving public health dilemmas aren’t Gates’ only passions. The man also plays a mean game of contract bridge, often in the company of fellow billionaire Warren Buffett. Here, in a June 12, 2006, photo from the World Bridge Championships in Verona, Italy, he tips his hand.

Not only is Gates the world’s richest man–he also has been lionized with a wax likeness at Madame Tussaud’s in Shanghai.