From pushing and helping to develop DOS and the PC to defining the modern operating system with Windows, Gates has left a perhaps unparalleled mark on the face of technology in the world today.  On Friday, after 33-years with Microsoft -- the company he cofounded with Paul Allen, a friend from school, in New Mexico in 1975 -- Gates will clock in his last workday with the company.

The move has been a long time coming.  In 2000, Gates stepped down as CEO and allowed his trusted, if a bit vociferous, friend Steve Ballmer assume the position.  The move was largely precipitated from the fallout of the major antitrust case in which Microsoft had been charged by the FTC of violations and found guilty.   Afterwards, Gates assumed the role of "Chief Software Architect".  In time, he would abdicate this role to Ray Ozzie and go on to become Chairman.

Now at last he is leaving the company.  Gates, ever lampooned and conversely idolized by pop culture, brought Microsoft into its period of greatest success with the rise of Windows 95, 98 and 2000.  During this era, Internet Explorer became king of the browser arena and Microsoft Office and its brethren became the undisputed leaders in productivity software.  Direct 3D and later DirectX became the standards of the newly formed 3D gaming industry.  In short, Microsoft dominated virtually every arena of personal computing software.

As Gates began to abdicate his responsibilities, some of Microsoft's more rocky times came into focus.  IE lost some ground to its first real competitor -- Mozilla Foundation's Firefox browser.  After a strong success with Windows XP, Windows Vista received poor critical reception and struggled to be adopted in the business community.  Meanwhile Microsoft received massive fines from the EU for its closed box software policies, which violated the EU's stricter anticompetitive laws.

Perhaps the greatest struggle for Microsoft has been its attempt to gain a controlling influence over the online world.  Try as Microsoft may, it has been unable to match first Yahoo, and now Google in terms of online relevance.  It tried to jump start its efforts with a Yahoo merger, but the talks fell through.

However, for its struggles the company has also had its successes.  The Zune music players were relatively well received, and while they did not turn out to be the iPod killer that Microsoft had hoped, they became a valuable new business.  Perhaps Microsoft's greatest new success was the creation of the Xbox game console.  From nowhere, the first Xbox surpassed long time stalwart Nintendo's next gen Gamecube console and only took second place to the wildly successful Playstation 2. 

In this generation the roles have reversed -- after an early lead thanks to its early release, Microsoft fell to second place to a reinvigorated Nintendo's wildly successful Wii.  Yet again Microsoft maintained a healthy margin over its third place competitor, in this case the PS3.

The mixed bag since cannot be pinned on any specific factor, but Bill Gates’ influence on the initial rampant success of Microsoft was undeniable.  His methods were a bit strange at times.  He was ruthless and competitive, not afraid to outmaneuver his competitors out of their livelihood, hiring the more talented of them in the aftermath.

He was equal parts guru and corporate shark, for days relentlessly dictating business policy, and then disappearing for months into his cabin retreat where he read papers from his best researchers and pondered the changing face of technology.  He would always return with profound memos which changed the course of the company; including his now famous 1995 "Internet Tidal Wave" memo.

Some fear that a post-Gates Microsoft will struggle to think and react like Gates.  Worse yet, CEO Steve Ballmer, a major guiding force in the company, will be departing in only 10 years.  With Ray Ozzie a similar age to Ballmer and Gates, the leadership line may fall into shambles.  However, Gates is going to do his part to keep the ship steady.   He will continue to chair board meetings and will continue to offer advice to Steve Ballmer, until he retires.

In his free time, Bill will devote more time to his charity work and family.  Bill and his wife Melinda have created the Seattle-based Bill and Melinda Gates Foundation, the largest charity of its kind.  Thanks to large personal donations from Gates and donations from people worldwide, the foundation has asset trust endowments of $37.3 billion and has committed to grants of $16.5 billion during its 14 years.  Gates and his wife plan to spend all of their money on charity within 50 years of their death.  For his efforts, he and his wife were TIME magazine's people of the year in 2005.

Gates hopes to use the money to focus on eradicating AIDS and malaria.  In short, he hopes in his retirement to modestly help conquer the greatest diseases afflicting mankind.

Bill Gates has given a couple farewell speeches in which he got a little teary eyed.  It’s understandable, though.  Even to the most hard-line critic of Microsoft, it’s hard to look at Gates and Microsoft's story and not feel something, not to feel moved by the force that this man created.  Gates may still be a shadowed presence at Microsoft, but as he fades into the twilight, the tech industry pauses to consider the departure of the man who defined it.