Installing 64 Bit Windows 8 From 32 Bit Windows 7

After the Windows 8 unveiling on Monday at the BUILD conference in Anaheim, the number one visited site was the blog of Scott Hanselman where he explains how to install Windows 8 to a VHD and boot to that VHD.

I followed his instructions step by step, but I had misadventures early on when the tool to make a bootable USB drive with the x64 ISO failed saying it had copied the files, but it couldn’t make the USB drive bootable.

At first I thought this was because the contents of the .ISO were more than the 8 gigs I had on my USB stick.  Turns out the ISO is only 5 gigs when mounted.  I had plenty of room free, but I couldn’t figure out why it wasn’t working.

The short answer is you can’t use the Windows 7 USB/DVD download tool to create an x64 bootable USB stick from a 32 bit OS.

I am running Windows 7 32 bit on a 64 bit machine.  Why?  Because the company I work for does not support 64 bit machines - specifically in the areas of VPN and Corporate Anti-Virus / Patching.  I knew my machine was capable of running a 64 bit OS and I really wanted to get my hands on the developer tools.

I set out to make the disk bootable on my own.

Before you do this, you will need a copy of Windows 7 x86 or Windows Vista x86.  You are going to need this to make your USB stick bootable.

So instead of running the nifty tool Scott showed in his post, I used DISKPART to format the USB drive, make it bootable using a Windows 7 x86 installation DVD, and then copy the files from the .ISO over.

First, mount the Windows 8 x64 ISO.  Right-click the ISO file and select “Mount”.

After you do this, the ISO will appear as a drive under “My Computer” where you can see the contents of the disc.  It’s 4.83 gigs total.

Now we need to start working on the USB stick.  I had an 8 gig stick.  Go ahead and insert your USB stick and fire up a command prompt.  We are going to use DISKPART to select the USB stick as a disk and format it.

WARNING: Be VERY careful during these steps. If you are not careful, you can erase your hard disk. Just look in the comments if you don’t believe me.



SELECT DISK 1 (replace the number with whatever disk number your USB stick shows up as)





FORMAT FS=NTFS (This can take a while)



OK, now our USB stick is formatted and ready for us to make it bootable. This is where you will need your Windows 7 or Vista 32 bit install disc.  Assuming that your install disc is in drive D and your USB stick is drive F, you will use BootSect to make the USB stick bootable in the following manner…


Now copy over the contents of the .ISO file.  Open up the mounted drive, select all and copy over to your USB stick.

That’s it!  You’ve just created a bootable USB stick containing 64 bit Windows 8 from a 32 bit version of Windows.

You can now pick up with Scott’s excellent article where he boots to the USB stick.

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