The average user only needs one Windows for his computer, but that sometimes isn’t enough. For instance, you may want to preview the upcoming Windows 10 on your computer without affecting your personal files on your current Windows system. Or maybe you have programs that only work with older versions of Windows. Follow this guide and learn how to have multiple Windows in one computer.
Adding another operating system to your computer is typically free of problems. But in case things go wrong, you should back up your files before you proceed.
Check if your computer has enough disk space for multiple Windows installations. Per the official system requirements, the 32-bit and 64-bit versions of Windows 7 or Windows 8 need 16GB and 20GB of disk space, respectively.
If your computer doesn’t have any operating system installed, install your first or main copy of Windows. If a Windows system is already installed, go to the Disk Management utility to shrink the volume for this system. Make sure you free up enough space for the second Windows system. Alternately, you can add another physical drive to your computer and install your second Windows on that drive.
Insert the installation media for the second version of Windows. Restart your computer and boot it using the installer. In the Windows Setup dialog during the installation procedure, choose Custom type of install. Don’t select Upgrade, because that replaces your first copy of Windows instead.
When you’re asked where to install your second Windows, find the space you freed up (or the additional physical drive). This should be listed as “unallocated space.” Be careful not to re-format the partition that houses your first Windows. Continue with the installation.
At this point, your computer now has two Windows. Every time you boot your computer, you should be directed to a screen where you choose an operating system to start.