Hit: MS-DOS (1981)

MS-DOS served as the main OS for IBM PCs during the 80s to mid-90s. 

Hit: Windows XP (2001)

Released in 2001, Windows XP proved popular enough to last a good decade. It was Microsoft's first mass-market OS to support Windows NT, a powerful multiprocessing, multi-user OS

Hit: Xbox (2001)

Xbox was Microsoft first entry into the competitive console market--and its first big jump into hardware. It was far from certain whether Microsoft was going to be able to compete with the likes of Sony's domination with the PlayStation 2, but the system came to become one of the major console players. Now currently on the third generation of the system with the Xbox One, it looks like Microsoft made the right decision. Still, the console business is hard to make money in. Some analysts believe Microsoft is losing $2 billion per year on the division.

Hit: Office 365 (2011)

Microsoft's Office 365 brought all the usefulness of the company's Office products to the cloud. Now you could sync up all documents on your computer to your mobile devices.

Hit: Surface (2012)

Microsoft's answer answer to Apple's iPad won mostly strong praise from tech pundits for its hardware, but continues to suffer for its limited selection of apps.

Flop: Microsoft Bob (1995)

Intended to make Windows easier to use with talking cartoon animals, Microsoft was much derided by the press and failed to attract customers.

Flop: Microsoft ME (2000)

The last Windows 9x series OS released, Microsoft ME suffered from serious stability issues.

Flop: Internet Explorer 6 (2001)

Internet Explorer 6 was the default web browser shipped with Windows XP and labeled by some as the "least secure software on the planet."

Flop: Windows Vista (2006)

Near the end of his tenure, Steve Ballmer said one of his biggest regrets was Windows Vista during his 14 years as CEO of Microsoft. Despite spending half a decade in development, the final product was an expensive, clunky mess.

Flop: Zune (2006)

Five years after Apple came out with the iPod, Microsoft tried its hand in a portable media player with Zune. Although not a complete failure, it was clear Microsoft had taken too long to release it and failed to compete with Apple in any significant way.

Flop: Kin (2010)

Microsoft's short-lived mobile phone for social networking. The home screen worked as an aggregator for all your social network accounts. Sales did not do well and the phone was quickly shelved.