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This guide assumes that you already have Windows 7 (or XP or Vista) installed. If you’ve already got Windows 8 installed, and you want to install Windows 7 as an additional OS, this guide might still work — but no guarantees.
First things first, you should backup any important documents. You shouldn’t lose any files during this process, but it’s better to be safe than sorry. See our Backup Masterclass for tips on how to backup your data efficiently and securely.
Windows Disk Management, shrinking a volumeWith that out of the way, hit Start, type diskmgmt.msc, and press Enter. This will open the Disk Management console. You should see a big (or small) list of all the drives currently attached to your computer.
Find the drive that Windows 7 is installed on (it should be marked as “Boot” or “System”), right click it, and click Shrink Volume. In the window that pops up, you ideally need a figure that’s around 50,000MB (50GB). If your hard drive is very full, this might not be possible. In theory the minimum install size for Windows 8 is around 20GB, but I really wouldn’t proceed without at least 30-50GB. If Disk Management refuses to shrink your volumes, you may need to try a third-party tool such as Paragon’s Hard Disk Manager.
Once the volume has been shrunk, a black, “Unallocated” region will appear at the end of the drive. Right click this and select New Simple Volume. Click through the dialog windows and give the new volume a memorable name such as Windows 8. Don’t change any other settings. This process will format the new partition, which may take a little while.
Installing Windows 8
At this point, all you really need to do is install Windows 8. You might opt to install a full version of Windows 8, or you can grab a 90-day evaluation copy. Either way, you want to slot the DVD (or USB stick) into your computer, reboot, and begin the installation process. (You may need to change the boot priority of your DVD drive/USB stick, which can be done in the BIOS).
Windows 7/8 multi-boot boot menuWhen given the option, select a Custom install (not Upgrade). On the next screen you’ll be shown a bunch of partitions/volumes. Select the one that’s labeled Windows 8 (or whatever you called it). Be absolutely certain that you’ve selected the right volume, then click Next.
The slick Windows 8 installer will now do its thing. It will reboot once or twice, but eventually you’ll be greeted with a multi-boot menu that allows you to select which OS you want to load (Windows 8, Windows 7, or any other OSes that’re installed). Windows 8 will load by default after a few seconds, but you can change it back to Windows 7 by clicking “Change defaults or choose other options” at the bottom of the screen. Voilà: You now have a PC that dual-boots Windows 8 and Windows 7.