Install Oracle’s Virtualbox so you can install Windows 10 as a separate Windows just like any other program you have. Download the ISO, save it to a folder. I have one that I also put my VirtualBox operating files into on my Desktop.
Once installed you click on New then go thru the wizard and browse to the location of the ISO then click on Start.
You will have a copy installed in about 20 minutes.
You can go thru the VirtualBox settings to allow copying files back and forth from your other Windows.
VirtualBox 4.3.28 for Windows hosts x86/amd64
Also install: VirtualBox 4.3.28 Oracle VM VirtualBox Extension Pack All supported platforms
https://www.virtualbox.org/wiki/Downloads
Windows 10 Build 10162
Product key: 8N67H-M3CY9-QT7C4-2TR7M-TXYCV
http://windows.microsoft.com/en-us/windows/preview-iso
The Product key: 8N67H-M3CY9-QT7C4-2TR7M-TXYCV did not work.
I got it at the link above but the message is that it won;t work with this edition. You can click Next and still use Windows 10.