UPDATE 1-Microsoft sold 40 mln Windows 8 licenses in month -exec

* Windows 8 sales outpacing Windows 7

* Number of actual users likely lower than license sales

* Intel-based Surface to be released January

SEATTLE, Nov 27 (Reuters) - Microsoft Corp has sold 40 million Windows 8 licenses in the month since the launch, according to one of the new co-heads of the Windows unit.

The new operating system is outpacing sales of Windows 7 at the same stage, Tami Reller, finance and marketing head of the Windows business, said at an investor conference held by Credit Suisse.

Reller was named as one of two executives to run the Windows unit after president Steven Sinofsky unexpectedly left two weeks ago. Julie Larson-Green heads the engineering side of Windows. .

Windows 8 and the Surface tablet were both launched on Oct. 26. Microsoft has not released sales numbers for the Surface.

The sales of 40 million Windows 8 licenses does not mean that 40 million users have adopted Windows 8. The bulk of those sales are to PC manufacturers, who in turn sell many machines to companies, very few of which are using Windows 8 yet.

According to tech research firm StatCounter, about 1 percent of the world's 1.5 billion or so personal computers - making a total of around 15 million - are actually running Windows 8.

The touch-friendly Windows 8 system and the Surface tablet are Microsoft's answer to Apple Inc's and Google Inc's domination of mobile computing, which has shunted aside PCs in favor of iPads and smartphones.

The first Surface, designed to challenge the iPad head on, is based on a chip designed by ARM Holdings Plc and does not run old versions of Microsoft programs. A slightly bigger version based on an Intel Corp chip that will run the full Windows 8 Pro operating system and be fully compatible with the Office suite of applications will be available in January, Reller said.