Prerequisites:
· Your BIOS must support booting to an USB device, and that functionality has to been enabled
        · An empty 4GB (or greater) USB device, and you’ve removed all other important files from the device. This process will WIPE IT CLEAN. You have been warned.
       · You must be using Windows Vista (or newer) DISKPART
Note: Don’t insert the USB device just yet. I’ll will tell you when.
Open a command prompt as administrator. From the C:> prompt, type:
diskpart
From the DISKPART> prompt, type:
list disk
Make mental note of the disks you have. Then, insert your USB device, and
list disk
again. You should see a new disk with a new number. That’s the number you’ll use in the next command:
select disk x
(x = the number for your USB device)
To make sure that there’s nothing on the USB device that will interfere with our booting; we will wipe out any and all partition information on the device. WARNING! This will wipe the USB device clean! It will delete and destroy any and all data on the device.
From the DISKPART> prompt, type:
clean
Now we want to create our primary partition for booting. From the DISKPART> prompt type:
create partition primary
Now we want to change to that partition and make it an active or bootable partition. From the DISKPART> prompt type:
select partition 1
When that step completes, type:
active
Next we need to format our active partition and assign a drive letter to the boot partition.
From the DISKPART> prompt type:
format fs=fat32 quick
When the format completes, type:
assign
You can now exit DISKPART and close the command prompt.
The USB device is now ready to boot. Next, just copy the files from the ISO (if you’ve mounted it using a tool which does this) or from the Windows 7 DVD onto the USB device.