FACTBOX: Microsoft's post-Gates leaders

(Reuters) - Microsoft Corp co-founder Bill Gates will retire from the company on Friday and move to a full-time role at his charitable organization, the Bill & Melinda Gates Foundation.

As Microsoft's biggest shareholder, Gates will maintain a role at the software company as its nonexecutive chairman. He will also take part in special technology projects.

Does Gates' departure leave a leadership vacuum at the company? Here's a list of the remaining leaders at Microsoft after Gates leaves:

* Steve Ballmer, Chief Executive Officer, 52

Ballmer joined the company in 1980 when Gates, a Harvard University classmate, talked him into dropping out of Stanford University business school to join Microsoft as its first business manager.

Since replacing Gates as CEO in 2000, Ballmer has been the main decision maker at the company, which has seen revenue more than double during that period.

Known for his histrionics and sharp intellect, Ballmer has said in interviews that he would stay at Microsoft for another "9 or 10 years."

* Ray Ozzie, Chief Software Architect, 52

Ozzie replaced Gates as the company's top software guru in 2006. He joined the company as chief technical officer in 2005 when Microsoft bought his software company called Groove Networks.

The white-haired, soft-spoken Ozzie competed with Microsoft for years, creating products like International Business Machines' Lotus Notes e-mail and calendaring software.

Ozzie is responsible for mapping out the company's "software plus services" strategy, which call on Microsoft's software to incorporate an online services element.

* Kevin Johnson, President, Platforms & Services Division, 47

Johnson has the dual task of protecting Microsoft's most important business, Windows, and building out its future cash generator, online advertising.

Since joining Microsoft in 1992, Johnson has taken on various roles in sales and marketing including being the head of worldwide sales.

He was one of the main drivers behind Microsoft's bid to acquire Yahoo Inc. After Yahoo's board rejected Microsoft's offer to buy the company, Johnson and his team countered with an alternative offer to buy Yahoo's search business and assume a minor stake in the company. That was also rejected by Yahoo.

* Christopher Liddell, Chief Financial Officer, 50

Liddell joined Microsoft from International Paper as CFO in 2005 with no background in technology.

The New Zealander has played a big role in transforming Microsoft from a company that hoards cash for a rainy day into a more aggressive spender for acquisitions and stock buybacks.

He has simplified Microsoft's earnings reports and he has been praised by Wall Street analysts as helping improve communication between the company and its investors.

* Brian McAndrews, Senior Vice President, Advertiser & Publisher Solutions Group, 49

McAndrews joined Microsoft in 2007 as part of the company's acquisition of digital advertising company aQuantive Inc.

With his extensive experience in the advertising industry, McAndrews is expected to spearhead Microsoft's efforts to create an online advertising platform.

Prior to being CEO of aQuantive, McAndrews had a background in broadcast and communications. He held executive positions at ABC Sports, ABC Entertainment and ABC Television Network.

* Craig Mundie, Chief Research and Strategy Officer, 59

Mundie took over as Microsoft's top technical visionary in 2006 in anticipation of Gates' exit from Microsoft this week.

Mundie's Microsoft career began in 1992 at the consumer platforms division where he was responsible for developing software for non-PC platforms such as game-consoles and handheld devices. Microsoft eventually introduced mobile phone software and a game console to compete with Sony's PlayStation.

He manages the company's $7 billion research and development budget, believed to be the largest R&D budget of any technology firm.

(Reporting by Daisuke Wakabayashi in Seattle and Syantani Chatterjee in Los Angeles)