The truth about how well Windows 10 is doing with Microsoft's most important customers

In January, Microsoft said that 75% of its enterprise customers are testing Windows 10.

New research from a company called Spiceworks shows that, while Windows 10 adoption in businesses is doing well, widespread adoption will probably still take a couple of years.

About 18% of Spiceworks customers are either testing Windows 10, or already have a bunch of employees using it, according to the company's research.

Spiceworks offers a popular network monitoring app used used at thousands of companies, which monitors hundreds of millions of devices. It scanned these devices and discovered Windows 10 on 18% of its customer's networks.

Of those using Windows 10, 40% are running three or more Windows PCs, indicating that they've rolled out Windows 10 for at least some employees. That means the majority of them are still just testing Windows 10 on one or two PCs.

Of course the Spiceworks information is third-party data that only provides a picture of a subset of Microsoft customers. But the report provides a valuable update on one of Microsoft's biggest product transitions in years.

Spiceworks users had previously revealed in a survey that about 40% of them would be taking the plunge and upgrading to Windows 10 within the first year the new OS was out. With 18% either using or testing, Spiceworks believes Windows 10 is still on track to hit that 40% true adoption number.

Although there's been a lot of emphasis on Windows 10 popularity with consumers, businesses are Microsoft's most important customers. They pay Microsoft a lot of money to use Windows on an annual basis, and their use of Windows also helps Microsoft sell other products, from Office to its cloud, Azure.

So Microsoft's success with businesses is critical. Fortunately, by every indication, it looks like Windows 10 will do fine with them.

Windows 10 is currently doing best in North American businesses (19% of them have some Windows 10 PCs on their networks) followed by EMEA (18%), Latin America (16%) and APAC (14%).

And, at this point, Windows 10 is more likely to be used in large companies than in small ones.