Steve Ballmer, Microsoft's CEO since 2000, is officially stepping down. Within 12 months, a special committee including company co-founder Bill Gates will name a replacement.

Ballmer, who has been at Microsoft since 1980, leaves a mixed legacy. Windows XP was generally considered a success when released in 2001, while the Xbox 360, unveiled in 2005, currently holds 44 percent of the console market, providing a nice platform to push media through the company's Xbox Live service.

The company's Business Division, which is responsible for Microsoft Office, has also remained extremely profitable, something that the gadget-obsessed press often overlooks, tweeted entrepreneur Anil Dash:

But speaking of gadgets: Microsoft was also responsible for the Zune, the sad competitor to Apple's iPod. The company nearly missed the smartphone revolution, before belatedly releasing the Windows Phone. And in the explosive tablet market, which is expected to grow fivefold around the world by 2017, Microsoft's horse, the Surface RT, reportedly lost the company $900 million in the last quarter.

In an internal memo to employees, Ballmer acknowledged that Microsoft's failure to release engaging hardware was part of the reason he was stepping down:

There is never a perfect time for this type of transition, but now is the right time… My original thoughts on timing would have had my retirement happen in the middle of our company’s transformation to a devices and services company. We need a CEO who will be here longer term for this new direction. [Microsoft]

Investors certainly weren't shedding any tears over Ballmer's departure. Shares in Microsoft jumped by 7 percent after the news broke, a welcome relief from the company's recent stock performance:

The excitable Ballmer was also never an inspirational figure like Steve Jobs, Amazon's Jeff Bezos, or Bill Gates. In fact, some of his public appearances were downright embarrassing:

Members of the press have been predicting this for years. In 2009, Dan Lyons noted in Newsweek that while "Google won the race for Internet search and keyword advertising," and Apple was winning the mobile industry, "Ballmer has missed every big new tech market of the past decade."

Not much changed over the next four years. While it's not clear whether Ballmer left on his own or was asked to retire, it certainly seems like Microsoft is cleaning house, with Xbox chief Don Mattrick leaving last month and Windows boss Steven Sinofsky stepping down last year.