Microsoft

Windows


Latest Stable Version: Windows 10 (build 10586.71)

Previous Major Release Editions: 
Windows 8.1, Windows 8, Windows 7, Windows Vista, Windows XP, Windows ME, Windows 98, and Windows 95

Latest Insider Edition: Windows 10 Insider Preview Build 14251

Description:
From Wikipedia

"Windows 10 is a personal computer operating system released by Microsoft as part of the Windows NT family of operating systems. It was officially unveiled in September 2014 following a brief demo at Build 2014. The first version of the operating system entered a public beta testing process in October 2014, leading up to its consumer release on July 29, 2015, and its release to volume licensing on August 1, 2015. To encourage the adoption of Windows 10, Microsoft announced that during its first year of availability, upgrades to the operating system would be made available free of charge to users of genuine copies of eligible editions of Windows 7, and Windows 8 after update to Windows 8.1."

Windows 10 Downloads: (More)

ISO - https://www.microsoft.com/en-us/software-download/techbench
Upgrade Tool - https://www.microsoft.com/en-us/software-download/windows10

Windows 7 Disc Images (ISO Files)
Microsoft - https://www.microsoft.com/en-us/software-download/windows7
You need a product key from a retail box

Systems

Surface

Current Versions: Surface Book, Surface Pro 4, Surface 3
Previous Versions: Surface Pro, Surface Pro 2, Surface Pro 3, Surface RT, Surface 2

Description:
"A feat of engineering and a work of art, Surface is a revolutionary new tablet from Microsoft. With casing made from ultra-light and highly durable magnesium, Surface will change the way you work and play. Run Office apps, watch movies in dazzling HD, catch up with friends and family. Do it all on one beautifully and thoughtfully designed device."

Where to Buy:
http://www.microsoft.com/surface/en-us

Xbox OS


Latest Stable Version: Xbox system software 10.0.10586.1026
Latest Developer Edition: Xbox system software 10.0.10586.1085

Current Version(s): Xbox One
Previous Version(s): Xbox, Xbox 360, Xbox 360 Slim, Xbox 360 Elite
Future Version(s): None yet

Description:
From Xbox One

"Xbox One is designed to start ahead and stay ahead. We’ve invested deeply in cloud infrastructure, and Kinect so game creators can deliver breathtaking new experiences. And so nothing will hold you or your games back."

Download Links:
Exclusive to Console

Where to Buy:
http://www.xbox.com/en-US/xbox-one

Windows Phone

This operating system will no longer be updated

Windows Phone
Latest Stable Version: Windows Phone 8.1
Previous Major Releases: Windows Phone 7, Windows Phone 8
Latest Developer Edition: Discontinued

Description:

"New features that bring you closer to the people, places, and things you care about. Simple refinements to make your phone a delight to use every day. And safeguards to help keep your data secure and your mind at ease. That's what makes the latest release of Windows Phone the best yet. Here's a sampling of the new, the cool, and the noteworthy."