As you have probably noticed yourself. Microsoft has made an effort to give everyone access to a free copy of Windows 10. While this might be a nice thing in the medium term future, this is NOT something we want users rolling out themselves. Unfortunately Microsoft has made it all too easy for that to happen. For those that have registered for a free copy of windows 10, it will download in the background and offer install without prompt. This is not something we can easily stop or control.
We as an organization will not be doing emergency rebuilds for people who run this install, they will have to be scheduled at the next available appointment we can make.
You will not be forced into this upgrade, but it seems that Microsoft will be making it very easy for you to start it on your own. The downloads will start tomorrow so please be cautious what you click on! As a general rule we wait for the first Service Pack on and operating system before rolling it out to a business environment. And even then it is usually based on security or functionality increases.