How to load Windows 7 onto a bootable USB key

Put an OS in Your Pocket

How to load Windows 7 onto a bootable USB key
To complete your Windows 7 power-user experience, you may consider dropping the whole darn OS onto a USB drive. Whether you carry it around in your pocket or toss it in a desk drawer, it's a perfect boot disk for emergency installs-including those times when you're working with a netbook or some other computer that lacks an optical drive. Even better, your install times will be significantly reduced, thanks to your key's flash memory-we shaved off minutes from our total install time.

Here's how to create a schmancy-fancy boot key for either Windows 7 or Vista-but not for other OSes, so please don't try! We've run a truncated version of this article in the magazine before, but because it was so incredibly popular-and so germane to this feature story-we've decided to share it again, this time with more detail and screens.

1. Format Your USB Key

Plug in your USB key and back up any existing data stored on it. You'll need to format the key (thus erasing existing data) before you can make it a bootable device. We used an 8GB key, but a 4GB key will also work.

2. Partition that Key in CMD
Open up a command prompt as an Administrator. You can do this by searching for cmd.exe in your Windows/System32 folder, right-clicking the executable, and selecting "Run as administrator." Alternatively, type CMD in the Start Menu search field and activate the command prompt using Ctrl + Shift + Enter.
You should now be under C:\Windows\system32 (assuming your Windows partition is the C drive). Type diskpart in the command line to enter the Disk Partition command-line tool, which lets you format and create partitions on active disks. Now type list disk to reveal a list of all your active disks, each of which is associated with a number. Make a note of which one is your USB key, based on the capacity. In this screenshot, our USB drive is Disk 2.

3. Format Away (Command-Prompt Style)

It's now time to enter a load of commands to properly partition the key, and format for the NTFS (did you know this stands for "New Technology File System"?). In succession, enter the following-and type carefully, Jimbo!

Select Disk # (where # is the number of your USB disk. We typed Select Disk 2 for this job)

Clean (this removes any existing partitions from the USB disk, including any hidden sectors)

Create Partition Primary (creates a new primary partition with default parameters)

Select Partition 1 (focuses operation on the newly created partition)

Active (sets the partition to active, informing the disk firmware that this is a valid system partition)

Format FS=NTFS (formats the partition with the NTFS file system. This may take several minutes to complete, depending on the size of your USB key)

Assign (this gives the USB drive a Windows volume and next available drive letter, which you should write down. In our case, drive "L" was assigned)

Exit (quits the DiskPart tool)

4. Copy Windows DVD to a Desktop Folder
Insert the Windows 7 installation DVD into your drive, and view the files that it contains. Copy all of the files to a folder on your Desktop. We put the disc contents in a folder named Windows 7.

5. Turn Your Key into a Bootable Device
Now, go back to your command prompt, running it as an Administrator. Using the CD command, navigate your way to the folder where you placed the Windows disk ISO files. Your command line path should look something like C:\Users\USERNAMEHERE\Desktop\Windows 7\ if you followed our lead on folder placement. Now type the following commands:

CD Boot (this gets you into the boot directory)

Bootsect.exe /nt60 L: (this assumes L is the drive letter assigned to your USB key from the previous step)

In case you're wondering, Bootsect infuses boot manager–compatible code into your USB key to make it a bootable device. Also be aware that if you're currently running 32-bit Windows Vista or 7, Bootsect will only work if you use the files from the 32-bit Windows 7 install disc. The Bootsect executable from the 64-bit version will not run in 32-bit Vista. Don't forget it!

6. Load the USB Key with Your Install Files
Copy all of the extracted ISO files into the USB drive. You don't need to do this from the command prompt. Just drag and drop the files from the Windows 7 folder into the USB drive using Windows Explorer. We also recommend copying your hardware drivers onto the same key so the installation wizard can find them.

Your USB key is now all ready to go! Plug it into your target system and make sure you enter the BIOS (typically by hitting F2 or F12) to temporarily change the boot order to allow booting from the USB key before your primary hard drive or optical drive. Now, when you plug the key into a machine, your system should automatically begin speedily downloading setup files off of the USB key and entering Windows 7 installation.