Windows 10 is starting to win over Microsoft's most valuable customers

Windows 10 is already looking like it's going to be a big hit with businesses.

Of the 75 million machines that downloaded Windows 10 in its first month, enterprise users made up about 2%, or 1.5 million, according to Windows IT Pro.

While that might sound like a paltry number out of the gate, it's actually not bad at all.

Companies don't lightly upgrade their business PCs. It can take them a year or more to even think about it, followed by months of planning and testing, and then months of installing and upgrading. So we won't see Windows 10 take off in a big way at companies until 2016 and beyond, market researchers predict.

Another indication that businesses are going to love Windows 10? Everyone from Microsoft's closest partners, like HP, to its long-time rivals, VMware, are praising Windows 10 and launching new services to help enterprises upgrade to it.

If you remember, HP had a few dicey moments with Microsoft during the early Windows 8 era. At one time CEO Meg Whitman called Microsoft out for becoming a competitor with the Surface PC, and HP launched a bunch of PCs that use Google's Chrome OS and Android OS.

A new chart from cloud security company Okta offers more evidence that Windows 10 is off to a strong start. Okta handles passwords for employees at 2,500 companies using cloud apps. It sees millions of logins daily by employees, and knows what kind of PC they are using.

It looked at the operating system that Windows users preferred and saw Windows 10 (the line in red) skyrocket in usage out of the gate. At 2% it's already zoomed past XP.

Microsoft still has a long way to go until Windows 10 overtakes Windows 7 machines. Windows 7 is used by over 85% of Windows users on Okta's network. But the early indications are looking good.