Microsoft's Windows 10 roll out has been going well, primarily driven by free upgrades for existing devices. While more than 200 million devices (including Xbox One consoles) are running Windows 10 after just six months, only around 22 million are active in the enterprise or education environments. Big businesses traditionally wait months or even years to install the latest version of Windows. It's largely because of the complexity of migrating thousands of machines, and internal applications. Microsoft wants enterprise customers to move to Windows 10 as soon as possible, and now it has big boost from the US Department of Defense (DoD) today.

The US DoD is planning to move 4 million machines to Windows 10 within a year. That's an aggressive timeline, and one that reflects confidence in Microsoft's latest operating system and a need to move to more secure software. The DoD's move to Windows 10 began in November after an internal memo directed all Combatant Commands, Services Agencies and Field Activities to rapidly deploy Windows 10.

Speaking to The Verge, Patrick Moorhead, principal analyst at Moor Insights and Strategy, says he's "struck" by the speed of deployment. "This implies that what they (DoD) were using was insecure and needed replaced immediately or as quickly as the government can work," says Moorhead. "The DoD, if it were a company, would be one of the largest enterprises spread out all over the world and wouldn't deploy Windows 10 if it weren't stable, secure, or pose a training challenge."

Alongside the deployment plans, Microsoft's Surface devices have now been certified and are available through the Defense Information Systems Agency (DISA) Unified Capabilities Approved Products List. This means the DoD could opt to deploy Surface, but it has not yet revealed its exact hardware plans.

The DoD's backing of Windows 10 is clearly a big boost to Microsoft's message of moving businesses off of Windows XP and Windows 7. Thousands of organizations still use Windows 7, and Microsoft is keen to avoid businesses sticking with it and creating another Windows XP situation. Security is a big challenge for all businesses, and the DoD's decision helps Microsoft positon Windows 10 as a secure alternative to Windows XP and Windows 7. "I think it's the best security proof point Microsoft could have," says Moorhead. "This at a minimum says Windows 10 as a base is really, really secure."