Microsoft prepares for grand unveiling of Windows 8

Firm sales numbers for Microsoft's Windows 8 and its new Surface tablet will not be available for three months, but it may be clear long before then if it has a hit on its hands.

"We can definitely gauge it by chatter," said Emily Chan, an analyst at Bernstein Research. "There is a slight learning curve, so I don't think we will see that big pop that iPad saw."

Microsoft is desperate for the new-look, touch-friendly Windows 8 to grip customers' imaginations, as it looks to regain ground lost to Apple and Google in mobile computing and shake up the moribund PC market.

I'd want to know the sales - and return rate - of the Surface.

Perhaps more important is its new own-brand tablet called the Surface, available only through its own stores and website, which will challenge Apple's iPad head on.

"I'd want to know the sales - and return rate - of the Surface," said Sarah Rotman Epps at tech research firm Forrester. "But those numbers will be hard to get since Microsoft is the only retailer."

Early reviews of the Surface have been mixed, generally praising the slick hardware, but faulting battery life and the limited software and applications available.

Some worry that the first Surface model, which runs on a stripped-down version of Windows 8 called RT that is not compatible with old Windows programs, will cause some confusion and dissatisfaction among customers.

The three models for sale on Microsoft's US website are already on back order, suggesting strong demand, but it is not known how many Surfaces Microsoft has manufactured.

"The fact it's back ordered is indicative that there's consumer interest," said Michael Gartenberg, an analyst at tech research firm Gartner. "How Microsoft introduces it, evangelizes it and explains it will determine long term success."

Microsoft has not said if it will reveal sales figures for Windows 8 or of the Surface before its next scheduled earnings on January 24. The company tends to trumpet good news and stay silent otherwise.

After the launch of Windows 7 three years ago, CEO Steve Ballmer waited only a month to announce strong sales. A year later, he waited only 10 days to report record-breaking sales of the Kinect, the motion-sensing add-on for the Xbox. But Microsoft has never shared the sales of Windows-powered phones, which have a lowly 3 percent of the market.

If Ballmer stays silent about Windows 8 sales, it might indicate a less than stellar performance.

"I would definitely take it a sign that it's not super, super strong, but I won't take it as something negative," said Chan at Bernstein, who is expecting 8.3 million Surface sales by the middle of next year.

That averages out at about 1 million a month, a third the rate of the iPad, which notched up its first million sales in 28 days and has now sold more than 100 million units, averaging about 3.2 million a month.

Gartner forecasts that Surface and other tablets running Windows RT will sell about 2.3 million units this year and 9.3 million next year, grabbing about 2 percent and 5 percent of the worldwide tablet market, respectively.