Microsoft today at the Mobile World Congress tradeshow in Barcelona launched the Consumer Preview of Windows 8. The Windows Store, which will be the marketplace for acquiring applications for Windows 8, launches today too, and all apps are free throughout the Consumer Preview period. Within the first two hours after launch Microsoft said the Windows 8 Consumer Preview had been downloaded in more than 70 countries. Read: Where to download Windows 8 Consumer Preview to find out how to get it.

See also: Microsoft Windows 8 review. See also: Windows 8 Consumer Preview in pictures.

The Consumer Preview builds on the previous Windows 8 releases, adding in the Windows Store with preview apps, cloud services, and hardware support for new hardware as well as a new Internet Explorer 10 build with a fresh rendering engine that is the heart and soul of the browser.

Head of Windows Steven Sinofsky described Windows as a 'generational change' and said it was the biggest update to Windows since Windows 95. He said that where in those days most people were new to computing, the challenge now was to break down the barriers between smartphones, tablets and the desktop. He added that the cloud had to connect all of these aspects, and that Windows 8's Metro interface would be a unifying force. "You can think of all this as a super fancy cloud connected clipboard," he said.

Microsoft introduced the idea of a Windows Account: like a Google or Apple ID that allows multiple devices to offer access to the same data, settings and levels of access. It's Windows Live on steroids and rebranded, in essence.

In summing up Windows 8, Sinofsky said: "Windows 8 is fast, fluid, and responsive. It's Windows reimagined. Windows is the only OS that spans form factors so you can use what you want to use."

He also said "You don't have to compromise because of the form factor you use. One OS will scale across the smallest tablets to the largest desktop [PC]", neatly teeing up Mike Angiulo to demostrate Windows running on Arm-powered tablet - the NVIDIA Tegra 3.

Microsoft also demonstrated Intel tablets and Ultrabooks, and showed off the much-trailed Metro connection UI, with 'airplane' mode and what Microsoft is calling "cost-aware" networking, that switches from cellular data to Wi-Fi in order to always use the cheapest method.

Angiulo and Sinofsky then delved into the world of touch, showing off an 100-finger multiple person touch, 86-inch optically bonded Gorilla Glass display, demonstrating the potential for multiple people to interact with the same screen: perhaps in a game. (And if you think an 86in PC is weird, it also had a pen for input...)

They then showed how Windows 8 could pull together any storage attached to a device, creating in effect one large disk or 'pool'. This looked undeniably impressive, but raises several questions: what happens when storage is removed if data is written to it? Is Microsoft in effect crowd-sourcing storage and utilising storage like a bank uses money (could be a bad example in the current climate...)?

Describing the ongoing Windows 8 release cycle, Sinofsky said: "The next milestone the release candidate, after that is the release to manufacturing, and after that is general availability." No fixed date was given for the consumer launch of Windows 8, and no pricing revealed.

Read our newly updated Windows 8 review.

Windows 8: tablet, all-in-one and laptop (and Arm devices)

Julie Larson-Green and Antoine Leblond demonstrated Windows 8, the Metro interface and the Windows Store, saying that Windows 8 users would have 'hundreds of apps' on their devices. Larson-Green showed off gestures and apps using a Samsung built preview tablet device, making named groups of apps when zoomed out, and pinching to see everything. She showed off Internet Explorer, navigating back and forth between pages with swipes to the left and right.

"It's really easy to take HTML5 games and turn them into full Windows apps," she said, as showed off a variety of apps and games.

Larson-Green also demonstrated some of Windows 8's multitasking capabilities: ways of minimising apps with a gesture, and pinning contacts - 'people' in Windows 8 parlance - to the screen, running a video while pinning IM windows to the sides of the screen, and so on.

Later, she returned to the stage to demonstrate Windows 8 on an all-in-one PC with a touchscreen. She said that the way users would interact with Windows 8 was not an 'either or' decision, but a question of which device happens to be at hand or most appropriate for the task in hand. "You're going to want to install Consumer Preview on a number of different machines and give it a try," she said.

She demonstrated using the Microsoft Account to access multiple devices, and searching all loaded apps without using a browser.

In showing off the Arm tablet from nVidia, Angiulo said that the same Windows features will run across Intel, AMD and Arm systems, but that on Arm, they will be connected even when on standby, so that emails and social posts are up to date from the moment you boot (a feature that will soon be available on some Windows 7 Ultrabooks). He showed off HTML5 video playing in Internet Explorer on the Nvidia tablet, and said there'd be all-new class drivers for easy printer, mouse, keyboard connections.

Windows 8: "Super fast, super fluid, no compromises."

Leblond showed off Windows 8 running on a laptop, using a Lenovo U300s ultrabook. He said that Microsoft had paid just as much attention to more traditional desktop computing as to portable devices, when it built Windows 8. He added that Windows 8 is just as comfortable to use with a keyboard and mouse as it is using a touchscreen.

Control-Alt-Delete has been replaced by simply hitting Enter, apps are opened with a single click. Leblond said that a mouse is better than your fingers at certain tasks, and vice versa, and suggested that Windows 8 was designed with this in mind. He succesfully demonstrated organising Metro apps and zooming using a mouse as his input device. "It's just as easy to navigate the system with the mouse as it is your fingers," LeBlond said. He said that apps didn't need to be designed to talk to each other in order to communicat, describing the Windows 8 experience thus: "Super fast, super fluid, no compromises."

"Windows 8 is an even better Windows than Windows 7," he added.

Windows 8: the desktop, and the Windows Store

Leblond demonstrated using Word on a Windows 8 system. "The desktop is great for working with multiple apps at the same time," he said, showing off Word and PowerPoint docked to the left and right of the desktop. That's right: the desktop. It's still in Windows 8 as Leblond demonstrated, but it becomes another app within the Windows 8 Metro interface, albeit a full-screen app. There's no Start menu, either.

Leblond also showed off the Windows Store. "We designed the store with one main goal: to find and discover applications," he said. "During the Consumer Preview period all of the apps in the store will be free, and as we go through the period we'll keep adding apps to the store."

He said that app developers were excited about working on Windows 8, which will have to be true in order for it to succeed. Indeed, Steve Sinofsky returned to the stage to say: "We're at just the beginning of an amazing opportunity for developers."

NEXT PAGE: Windows 8 Consumer Preview - the details, and quotes from today's event >>