Ten years ago, Microsoft's Bill Gates turned over the CEO reins to Steve Ballmer. What came next was a decade-long wild ride.Ten years ago on Jan. 13, 2000, Microsoft's Bill Gates turned over the CEO reins to Steve Ballmer, who emphasized then that the Internet would be the target for much of the company's new software development efforts.Fast forward to today's product integration announcement with HP and events over the past year with cloud computing and Windows Azure, and Ballmer's words ring true. Back in 2000, Microsoft was still under threat of being broken up by the Department of Justice. Today, Ballmer is trying to meld enterprise and cloud computing.Mobile, search key challenges as Microsoft's Ballmer moves beyond a decade as CEOHe has spent the past decade working through lawsuits, mergers, acquisitions, competitive battles and, of course, new software, including last year's official launch of Windows 7, which could become the legacy of his leadership at Microsoft.He has put his stamp on the company, including a multi-year reworking of the executive staff. Under Ballmer's watch, company revenue is up 163%, but the stock price is down 39%. Ballmer oversaw Microsoft first-ever mass layoff last year and was greeted in 2010 by the Newsweek prediction that he would not survive the next 12 months.The CEO has been noted for his sharp, and sometimes loose, tongue. In 1999, the year before he took over for Gates, Ballmer's comment that tech stocks \u2013 including Microsoft \u2013 were overvalued cost Ballmer $1.2 billion on paper as the market went on a two-day tank that eventually dragged the Nasdaq composite index to a five-month low.And Ballmer's developers, developers, developers rant \u2013 and accompanying YouTube video documenting his dance moves \u2013 are legendary.But Ballmer is nothing if not tenacious and optimistic.In November, he sat down with Network World and reflected on the past 10 years. He said he takes pride in where the company is positioned today and its outlook for the future. When asked what were his greatest successes, greatest challenges and greatest regrets over that time, he chuckled and said. "Well, I probably had all three of those in spades."He listed his successes as a tripling of profits in the past 10 years. "Which, ultimately matters if you are CEO; that is kind of an important dimension," he said. "That is off a high base, so I feel pretty good about that."He said 10 years ago Microsoft was not considered a serious player in the enterprise but that perception is gone today. "I feel good about that," he said."And I feel good that despite the hubbub of 10 years ago what was going to happen with Linux, with open source, and Internet and OpenOffice, we have done really well innovating and driving the kind of innovation in Windows and Office and Windows Server that has served us well."Ballmer is also clear on the areas that perhaps keep him up at night."I wish we were a little further in the market and had a little bigger position in search, no question about that," he said. "We jumped on mobile early, and while we are in the mix we should have distanced ourselves from competition as opposed to just being in the mix."With the popularity of the Apple iPhone and Verizon's Android mobile offering, and the lukewarm reception critics gave Windows Mobile 6.5 phones, the mobile challenge will likely continue for Ballmer.Ballmer matter-of-factly said there are plenty of regrets, implying there is no time to dwell on them."Most of the regrets are 'hey, I wish we had done something earlier, I wish I had made a decision a little bit differently,' but mostly I feel good about the things there are to be proud about."Those things, he said, include being well positioned for the future. "We are investing in some amazing things, and I think we are poised to continue to be leader of our industry, but a lot of competitors are vying for that as well."Follow John on Twitter: twitter.com\/johnfontanaThis story, "Ballmer took Microsoft reins 10 years ago with focus on Internet," was originally published at NetworkWorld.com. Follow the latest developments in software at Network World.