Microsoft has sold 40 million Windows 8 licenses since October 26.

Tami Reller, the Chief Marketing and Financial Officer for Windows announced the tally during her appearance at the Credit Suisse Annual Tech Conference on November 27.

Microsoft had not released any sales figures for Windows 8 other than saying the company sold 4 million upgrade licenses of the operating system to those with previous versions of Windows during the first three days it was available. Microsoft launched Windows 8 commercially on October 26.

How does this compare to Windows 7 sales? Microsoft said it had sold 60 million Windows 7 licenses from the end of October 2009, its launch date, to the end of January 2010 December 2009. So that's 60 million Windows 7 licenses sold in two months. So far, Microsoft has sold 40 million licenses of Windows 8 in one month.

Reller did not release any sales figures for Microsoft's Surface RT tablet/PC devices, which also have been on sale since October 26. She did reiterate that Microsoft will have the Surface Pro, the version of the Surface running Windows 8 Pro, availalble in January 2013.

Reller spent much of the first 25 minutes of her presentation about Windows 8 and Surface reiterating Microsoft's design philosophy. She cited a number of statistics meant to show that users were positive about the Windows 8 PCs and tablets that have are in the market and coming to market in the coming months.

"For $39.99, you get Windows 7 made even better," Reller said. (That $39.99 figure is the cost of an upgrade license during Microsoft's current promotion.)

Reller is one of the two primary leaders in charge of the Windows division -- along with the new head of Windows engineering, Julie Larson-Green -- now that former Windows President Steven Sinofsky has left the company. Sinofsky's immediate departure was announced a couple of weeks ago.

Reller was asked about Sinofsky's departure during the Q&A part of her presentation. She emphasized that the foundation of Windows is in great shape and that the Windows unit has a deep bench. She said she'd personally miss working with Sinofsky in the future.

Reller shared a few other stats during her remarks including:

Microsoft now has certified 1,500 PCs and tablets for Windows 8, up from the 1,000 devices it had certified a month ago at launch

The number of apps available in the Microsoft Store has doubled since the launch. (She didn't talk about the total number of Windows Store/Metro Style apps available currently, but WinAppUpdate pinned that number at just over 21,500 worldwide this week.)

A number of applications available in the Windows Store have crossed the $25,000 revenue mark. (Again, no specifics were shared here.)

Without acknowledging directly the critics -- including yours truly -- who've found Windows 8 less than intuitive, Reller said that users are finding Windows 8 "easy to understand and embrace." She said users are exploring Windows 8 and enjoying learning it, from Day 1.

Based on customer feedback and information gathered by Microsoft's customer support organization, "We do know that customers do, indeed, 'get' the product," she said.

She said that over 90 percent of those purchasing Windows 8 and Windows RT devices are using the Charms on Day one. (Charms are the icons that provide search, sharing and other basic functions that can be found by swiping in from the right on a Windows 8/Windows RT device.) She said they are using search between two to three times a day every time they are on their devices. And she played up Microsoft's data that found more than half of the users are using the Windows Store on their first day.

Update: Yes, we don't really know exactly what "licenses sold" includes and does not. Sold to consumers? Sold to channel? Includes licenses grandfathered in through volume license agreements. I've asked Microsoft to see if officials will clarify. If they do, I'll add an update here.

And the official word from a spokesperson: "We have nothing more to share."