Windows 10 to be free to users of Windows 7 and 8 - but will Microsoft's 'as a service' aspirations put people off?

Augmented reality visor, more on Universal Apps for Windows Phone and 4K Surface Hub display also unveiled by Microsoft

Windows 10 will be free to users of Windows 7 and the much-maligned Windows 8 operating systems for the first year, as Microsoft looks to shift to an "OS-as-a-service" model.

In the process, the company wants to move from iterative operating system releases to rolling releases.

"In the next few years, you could think of Windows as one of the biggest internet services on the planet. The question of 'what version are you running' will cease to make sense," said Microsoft executive vice president of operating systems, Terry Myerson.

However, the strategy remains shrouded in confusion as little new detail was offered about this potentially game-changing Windows 10 development at today's event in Redmond.

And, after the live feed ended, Microsoft CEO Satya Nadella was widely reported to have told the press that "there is no fundamental shift" to the Windows business model in terms of supplying Windows 10, which suggests there will be no subscription fees to pay on an ongoing basis.

Whether this means a flat-rate will entitle users to purchase Windows 10 before paying for the next upgrade is unclear, but Microsoft did confirm that OEMs will have to continue paying Microsoft fees to cover the cost of Windows 10 for their own hardware, and there will be no cost to users for support.

While perhaps the most enterprise-relevant part of today's announcements, Microsoft only offered that more would be revealed at the annual Build conference in April 2015.

More on Universal Apps

Aside from the beginnings of a change in Windows 10's delivery and maintenance, the company also elaborated on its "OneCore" or "Universal Apps" ideas, which included a seemingly significant leap for Windows Phone.

Demonstrations included a Windows Phone interface incorporating Office app extensions with the famous (or dreaded) "ribbon" bar to help editing and collaboration on documents.

Cortana, Microsoft's answer to Apple's voice-controlled assistant Siri, was also officially welcomed into the Windows 10 desktop family, as corporate vice president of operating systems at Microsoft, Joe Belfiore, suggested that having the disembodied female voice resident in a PC "is almost like having another member of the family".

Microsoft also made official the recently-rumoured "Project Spartan" web browser, which is being touted as the replacement for the perennially unpopular Internet Explorer, and seems to share many elements of the existing "Modern" build of Internet Explorer on Windows 8.

Working with the "HoloLens"

After showing off Surface Hub, a 4K-ready wall-mounted touchscreen that Microsoft hopes will exist primarily as a OneNote-equipped enterprise collaboration tool, the HoloLens was also revealed.

While demonstrators kept referring to the wearable device's features as "holograms", this Oculus Rift-like visor seems to display "augmented reality" graphics, which enable the user view the world through a camera lens, with computer-generated effects overlaid.

The device was demonstrated running impressive games of Microsoft's recent acquisition Minecraft in living rooms, but it was also shown as an enterprise creativity and collaboration tool, with a demonstrator building a model helicopter from component parts that could be printed. Another individual used the device to design parts of a motorbike, which could be shared and examined by other users, both on and off the device.

For a two-hour presentation, Microsoft's announcements were scant on details, with the company instead choosing to pack in a wealth of new information.

CEO Nadella appeared at the end to explain how he feels Windows 10's new "as a service" state, coupled with new usability across devices, is "about innovation coming forward - new categories and experiences".

He continued: "We're not bolting on apps, we're seamlessly incorporating experiences."

Computing has already asked Microsoft for further comment and clarification on licence frameworks for the enterprise, and will report back as soon as we know more.