Working with a .VHD file
A virtual environment is great for experimentation, but if you want to find out how Windows 8 runs on your hardware without sacrificing an entire partition you can use a .VHD file. In this case the start-up disk of the OS is a file on you hard drive. It has a bit of a negative impact on writing speed, but it keeps your hard drive from being unnecessarily cluttered.
You need an installation disk with Windows 8. You could burn the ISO file to a DVD, or create a bootable USB-stick with Windows 8 on it. To do that you need a USB-stick of at least 4 GB and the Windows 7 USB/DVD download tool that you can download here: http://www.microsoftstore.com/store/msstore/html/pbPage.Help_Win7_usbdvd_dwnTool
Here you can download the Windows 7 USB/DVD download tool.
The Windows 7 USB/DVD download tool turns a normal 4 GB USB-stick into a fast installation disk.
Once you've created either an installation disk or bootable USB-stick, you start it up. The first screen asks you to choose your default country and keyboard settings. On the next screen, do not click on "Install now" but on "Repair your computer". Then on "Troubleshoot", and then on "Advanced Options" where you select Command Prompt. That will take you to the command mode of the Windows 8 installation disk, and the folder is called X:\Sources. Now you have to decide where to put the .vhd file. The sequence of folders is different in command mode, so it helps to check the content of the available drives first.
In case your knowledge of MS-DOS has become a little rusty, you first write "C:", press Enter, and then write "dir" and press Enter again. This will list the contents of drive C. You can repeat the process for each drive letter. We wanted to save the .vhd file on the D drive. The next step is to start Diskpart, by typing "diskpart" in the command prompt when you are on the D drive. Then you create the .vhd file, in our case on the D drive with the name windows8.vhd (or another name). We advise a volume for the virtual drive of 20 GB at least. In the case of this .vhd file all of that space will be reserved. Then you select the file, and link it to your system. Now you can exit the program, and return to the X drive where you can start the setup in X:\Sources. Now you can follow the standard steps, and now you should see a new 20 GB hard drive (Drive 1) on which you can install Windows.
These are the steps for creating a .vhd file in the Command Prompt
Type each command, then press enter.
-create vdisk file=D:\windows8.vhd maximum=20000
-select vdisk file=D:\windows8.vhd
When you are ready to remove Windows 8, you can just delete the .vhd file. In order to also get rid of the Windows 8 bootloader, you need to perform automatic repair with a Windows 7 installation disk. By typing "msconfig" in the command prompt you can access boot options and change them.
Choose "Repair your computer" instead of "Install Now"
Then "Advanced Options"
Then "Command Prompt"
Now you can run Diskpart.
Via msconfig you can change the boot options