The HP device is also expected to go on sale later this year.
"It's a beautiful little product," said Microsoft boss Steve Ballmer.
During his keynote address at CES, Mr Ballmer demonstrated the machine in front of an audience of over 3,500 press, bloggers, analysts and industry peers.
He also showed off two other tablet computers - one made by Archos and the other by Pegatron Corp.
Reaction to the as yet unnamed device was somewhat subdued.
"What we saw confirmed my worst suspicions that this is your standard Microsoft software in a slate form," Paul Miller, senior associate editor of technology website Engadget, told BBC News.
"It's an interesting product in itself but Microsoft could have gone further. It's not anything new in terms of software and that is what you really need to make a device like this make people want to buy it."
Analysts warn that a glut of these products will confuse consumers
However, technology blogger Devin Connors of Tom's Hardware did not agree.
"It looked really good given the short amount of time we saw it for and it has Windows 7. Everyone loves Windows 7 and putting it in a device the size of an e-reader is probably going to be a winning combination."
The lack of enthusiasm for the product was in part due to speculation about what - if anything - Apple may launch.
Rumours of a Apple slate - dubbed the iSlate - has dominated the blogosphere in recent weeks, although there has been no formal announcement by the Cupertino-based company.
"Apple tends to change the game and this Microsoft/HP tablet didn't blow them out of the water," said Dean Takahashi of tech blog VentureBeat.com.
"How successful it will be is up in the air, but HP is the biggest technology company in the world and can certainly put a lot of muscle behind the device," he told BBC News.
Microsoft is the world's biggest software company.
This is not Microsoft's first attempt to introduce a tablet or slate-like computer.
Back in 2002, the company introduced a tablet PC version of Windows XP, which failed to take off.
The form factor is around 10 years old.
Windows 7 replaced the much hated Windows Vista
Analysts however believe these new entries should give the middling $950m (£597m) US market for tablets a much needed jolt.
"Apple could do for the tablet market what it did for smartphones with the iPhone," analyst David Daoud of IDC told USA Today.
Other industry watchers fear that consumers might be a little wary with so many companies all rushing at once to bring out new devices.
"With this market awash in products, customer confusion is what we have for certain," said Silicon Valley analyst Rob Enderle of the Enderle Group.
In his address, Mr Ballmer also focused on new PCs, software and the success of Windows 7 which was released last October.
"The biggest hit of the year was Windows 7," said Mr Ballmer.
"Windows 7 is by far the fastest selling operating system in history."
The software boss cited figures from the market analysis firm NPD that said that since the launch of Windows 7, sales of consumer PCs in the US over the latest holiday period were up more than 50% from the year before.
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