Installing Windows 7 from USB

As netbooks get more popular and optical drives become less and less of an assumption, there are many times when a USB install of an operating system is a far better choice than the old DVD/CD we know and love.

When working with USB keys, whether to install or run the OS itself, in the past it was quite the chore and involved much wrestling of vendor utilities.

Thankfully, the world has changed and nowadays installing from USB is a rather easy process --- provided you have a working Windows install or can borrow one.

For Windows 7, it all begins by going to this page and downloading the Windows 7 USB/DVD Download Tool.

Double click on the download's icon and you will be presented with this dialog:

The standard install process occurs from this point, and nothing surprising should happen.

Once installed, start-up the application itself (it rudely likes to put an icon on the desktop) and you get the below dialog that is asking for an ISO image. Microsoft's recommended path is to have the ISO downloaded from the Microsoft Store, but any old Windows 7 install CD image will work as long as it is an ISO.

In this screen we choose "USB device":

After this we point the tool at our USB device, at which point it will proceed to format the device.

And now we wait:

Hopefully everything worked as it should have --- in my case, it did not.

I kept receiving errors complaining about not being able to run BOOTSECT.EXE, this was because I was using a 32-bit Windows XP machine to create a 64-bit Windows 7 install media. For reasons I don't understand, the tool decides to use the BOOTSECT available from the ISO, not the one that the host machine has. The solution was to get a 32-bit version of BOOTSECT and drop it into the tool's local appdata folder (the tool's troubleshooting says that folder is C:\Users\username\AppData\Local\Apps\Windows 7 USB DVD Download Tool, but it is slightly different in Windows XP). I had to do a bit of searching, but I was eventually able to find a 32-bit BOOTSECT and had to restart the process again.

At this point you now have a USB drive that will install whichever version of Windows 7 that the ISO you used was. But with a simple trick, we can make the install process ask us which version of Windows 7 we want to have installed.

Navigate to the USB drive's sources folder and delete the file named ei.cfg

Now we can reboot the host machine and start to install Windows 7. During start-up, make sure that you select booting from USB from your BIOS or boot menu.

After the install process starts, you are presented with this screen:

Once your selection is made, you should select the Windows 7 version that you have keys for, and the install process will continue like any other Windows 7 install.

And there you have it, this is actually a very simple process. There was no need to dive into the Command Prompt, nor use any third-party utilities.

If you remove ei.cfg you now have a handy USB key that many sysadmins will find useful in their day-to-day activities.