After three release previews and over a year of testing on PCs, laptops and tablets around the world, Microsoft launched Windows 8 at an event in New York.
Steven Sinofsky and Ballmer took their turns on the keynote stage for a presentation that was at times a little wooden and rambling.
PC Pro's Tim Danton was in New York to bring you all the news as it happened.
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Obviously Microsoft has its hands tied with all the partners and the previews we've had, but that has to go down as one of the most pointless keynotes in a long, long time. Thanks for joining us anyway!
Wait, that's actually it? The whole thing? Front row looks a little disbelieving but yes, I do think it’s over.
Ballmer wants us to head to a retail store and try it for ourselves. And that's it. He just talked for about ten minutes without saying much.
"Stop talking about all these features, start showing them. They're good features, you're making them sound dull," tweets Barry Collins from his day off. Editors never stop working, eh?
Steve needs to look a bit more chirpy. Come on Steve, give us a smile.
"We've re-invented the smartphone around you."
Now bigging up Windows Phone 8. That launch is on Monday.
I’m starting to lose track of the number of times I’ve heard the word magical during this launch.
Lots of Bing stuff. Bing Maps, Bing Sports, Bing Crosby etc. Does anyone use Bing?
Good thing Ballmer became head of Microsoft. Otherwise he’d make a mean-looking mafia boss.
"Are these new designs PCs? YES. Are these new designs tablets also? YES."
"For the first time, Windows has first-rate tablets." Hard to disagree with that - the bit about them not being first-rate before, we mean.
"Windows 8 shatters perceptions of what a PC really is."
Time for Ballmer at last! He's already more relaxed and natural than anything we've seen so far.
I think we've just seen about 15 devices there, with no real information given. Presentation is all over the place.
Whoops to greet Surface, some from people to my right. I really hope they’re MS employees too.
Lenovo Yoga now being demoed - read our hands-on here.
Tough thing for MS is that these apps are mostly old from iOS and Android, but totally redesigned for Windows 8. Hard to get excited for things like UrbanSpoon.
Wikipedia app looks nice. Properly designed for Windows 8.
Apps in Store have doubled over the last few weeks (as of yesterday it was actually fewer than 8,000 but MS isn't saying any numbers).
This is quite nice. A 27in 2,560 x 1,440 Dell all-in-one, then the convertible Dell XPS 12. Not a lot of clapping.
Showing off some Lenovo and Acer kit, nice tablets, nice laptops. this one reconnects to the internet in one second. This is one of the most stilted presentations we've seen in a while.
You can tell where the Microsoft employees are – lots of clapping and whooping from the left-hand side, nothing from the right-hand side.
More software stuff. So far it's all stuff anyone who's used Windows 8 will know.
The two demo people are doing all this as if they're telling the news to each other. It's a bit odd.
Lenovo laptop on stage boots 33% faster than Windows 7. This demo isn't exactly polished.
Now Xbox Music - you can read our first thoughts on that here.
Ten-point multitouch will make the internet better apparently.
Currently demonstrating the lock screen and customisations. With cheesy chat between our two demo hosts.
"When you're having fun you're more likely to explore." She's talking about gestures. Odd.
Now some hardware at last.
Windows Store has more apps than any competing store did at launch, apparently. Different world now though, surely.
New Ivy Bridge Ultrabooks coming today, including touch.
Every new copy will come with a simple How-To. That's good news.
Sinofsky looking cool and relaxed in jeans, t-shirt and jumper. And it’s hot in here.
Touch "ushers in a new era of scenarios and apps".
Windows 8 has had 1.24 billion hours of testing in its various beta stages.
Lots of Windows 7 talk to start.
A man's walked onto the stage! But he's a photographer taking a pic of the audience. How very disappointing.
First whoops of the morning (it's 11am New York time) from enthusiastic US audience... but no sign yet of Big Steve
Tim's on his way into the keynote, which is due to start at 4:15pm...