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How to Dual-Boot Windows 8 and Windows 7 Without Drive Partitioning?

Although we've shown you quite a few ways of making the computer run on pure Windows 8 elixir, like the classic upgrade from Windows 7, installing the OS on a virtual machine and dual-booting, there is always scope of making things better.

In our previous article, we've shown you how to dual-boot Windows 7 and Windows 8, a method which required partitioning your drive to create an empty partition for Windows 8 to use. This method may not go down well with many as Windows 8 is still in the making and giving away a chunk from the storage space might not please everyone. For this we have decided to show you how to dual-boot your system without repartitioning. Instead of splitting the drive, we will use a virtual hard drive, also known as a VHD.

In a few words, you virtually create a hard drive, which will consume storage space from one of your existing partitions. If you like, you can view this drive as a big ISO image, which can be deleted right away.

Those that already know what are we talking about; you may also know that this method is somewhat complicated. In the following steps we are going to use the friendliest layout, creating the VHD from the GUI and peppering it with some PowerShell script based spices.

It is worth mentioning that Windows 8 can be dual booted with any other OS but the steps described below use Windows 7 as the primary choice. We are also going to use an ISO mounting program called Daemon Tools (opens in new tab), but you can use any other variants.

Part 1: Creating the VHD

1. Press the "Windows key" + R buttons to open the Run menu.

2. In the Run window, type "diskmgmt.msc" and hit Enter.

3. Click on the "Action" button and then on "Create VHD".

4. Browse to the location where you want to save the VHD, assign it a size no less than 20GB and then check the "Fixed size" radio button.

5. Once the VHD is created, it will appear as unallocated space and with a black header. Right-click its icon in the left sidebar and choose Initialize Disk.

6. Leave the settings as they are and click OK on the next window.

7. Right click on the black header of the same drive and select "New Simple Volume".

8. Once the wizard appears, go with default settings until the end, except the window where you have to assign it a name. Choose one that will differentiate the disk from others.

Part 2: Installing Windows 8 developer preview on the VHD

1. Navigate to Start->All Programs->Accessories-> and right click on the Windows Powershell then choose "Run as Administrator". A blue window will appear.

2. Type "Set-ExecutionPolicy RemoteSigned" and hit Enter. When prompted, type "y" to confirm the execution and do not close the window during the next steps.

3. Download this script (opens in new tab) and place it on the root of "C:\".

4. Now right click the above file and go to "Properties". While here, hit the Unblock button and then OK.

5. Download Windows 8 developer preview (opens in new tab) and then mount the image (steps 2-4 from here).

6. Back to the PowerShell, type "cd c:\" and hit Enter.

7. Now type ".\Install-WindowsImage.ps1 -WIM X:\Sources\Install.wim -Apply -Index 1 -Destination Y:\", where X is the letter assigned to the mounted drive that holds the Windows 8 image and Y is the letter assigned to the VHD. Change these values according to configuration on your system. If successful, you should see something like "Applying Windows Developer Preview to Y:\".

8. Once complete, open the command prompt ("Windows Key"+R -> type cmd.exe and hit Enter).

9. Type "bcdboot.exe Y:\Windows" and press Enter again. As above, Y needs to be replaced as per the drive letter on your system.

10.Restart the computer and Windows 8 will appear as a new boot option.