I’m not the first blogger to rant about Windows 8. It’s been out there for over a week I think, downloadable for everyone from the Microsoft preview site. But remember the version that is released now is not feature complete, nor is it in any way, form or shape close to the finished product. It’s released with the sole purpose of beeing a plattform where developers can validate their Metro apps in. Metro by the way is the new GUI that is launched with Windows 8 (if this is the final name of the product). There are sure to be some big changes before it’s time for RTM.

So if you wan’t to test on your real hardware but wish to keep your installation clean this is how to do it!
This tutorial works both for the Server and Client Preview version.

1. First download the Preview version from the Metro developers page.
http://msdn.microsoft.com/en-us/windows/apps/br229516

2. Download the WIM2VHD Tool
http://archive.msdn.microsoft.com/wim2vhd

3. Mount the downloaded Windows Developer Preview ISO
You can use Daemon Tools, Virtual Clonedrive or burn it to a CD and slot that in. If you are using 7-Zip you are also able to open it there. What we need inside is the file located in \sources\install.wim.

4. Convert the Install-file to a VHD
Launch a elevated prompt, then type the following, subsitute the paths with your own paths.

CScript x:\path\wim2vhd.wsf /wim:”x:\sources\install.wim” /VHD:”d:\VHDBoot\W8DP.vhd” /size=30000

5. Update boot-loader
This is the first step that is potentially dangerous for your machine. You will need to mount the vhd we produced in the previous step and install the Windows Developer Preview boot-loader. Launch a command-promt as admin and execute the following commands (on your own risk!) Replace V with the drive-letter of your vhd when it have been mounted and assigned.

diskpart
>select vdisk file=d:\VHDBoot\w8DP.vhd
>attach vdisk
>select partition 1
>assign
>exit

bcdboot.exe v:\windows

diskpart
>select vdisk file=d:\VHDBoot\w8DP.vhd
>detach vdisk
>exit

6. Save the VHD
Copy the VHD to another directory to always be able to substitue the VHD whenever you need without needing the install.wim file again.

7. Reboot
Select Windows Developer Preview in the boot menu.

Enjoy!