Windows 8 multi-boot or dual-boot is an option that allows you to install both Windows 8 and Windows 7 on your computer. You can also install previous versions of Windows or Linux and boot the system to preferred operating system but this instructions assumes you have Windows 7. It's better to install the older version of the operating system first because that will override the boot store.
To setup a Windows 8/7 mutli-boot, follow the instructions below:
1) First backup your system in case things don't go right
2) Right click
Computer and click
Manage
3) Create new volume for Windows 8 by shrinking the space of existing drive. If you have multiple Hard Drives, install Windows 8 on one of them and Windows 7 on the other. In this example, we are using multiple drives.

4) Boot the computer with Windows 8 DVD
5) Choose the language/Time/Keyboard settings and click Next.
6) Choose
Custom Install on the Installation Type dialog box then choose the
new hard drive or
volume and click next

7) Let the Windows 8 run its course to install Windows 8

8)
Personalize your computer once the installations is done (computer name, windows account, administrator username and password, color scheme, network settings, etc)
9)
Restart the computer once the installation is complete and you should have an option to boot to Windows 8 or Windows 7
