A bootable USB drive is a very handy tool. It allows for much faster install than from cd/dvd drive(personal testing showed about 25% less time to install). You can also use it to install an operating system on a computer with incompatible/no cd/dvd drive such as a netbook.
Personally, I tried installing Windows 7. I run Windows xp on my main partition, but theres no way to upgrade from xp, and for whatever reason during install, the windows 7 installer said I did not have the drivers for my dvd drive. So I set out to find a solution to that, which is what I will be sharing with you.
First, make sure you have a flash drive that is the appropriate size. Most likely this will be at least 4GB for Windows Vista or Windows 7. You can likely fit an XP install on a 1GB flash drive.
Note: This will erase all data on the usb drive. Backup any data you wish to save.
Run the command prompt. To do this go to “Start->Run”. Type in “cmd”. Or simply search the start menu for “cmd”.
Formatting the drive (Windows Vista/Windows 7 instructions)
We will be using diskpart.exe to change the properties of the usb drive. This should be included on any Windows Operating System.
Type in the following commands:
Comment: The “diskpart” command will open the diskpart.exe command prompt tool.
Comment: The “disk list” command will list all you main disks. After you run this command, find the number of the usb drive you wish to use. I will call this disk x for future reference.
select disk x
Comment: The “select disk x” (where x is the disk numer obtained from the previous command) command will select your chosen disk. (Example: select disk 2). You will see a message that says your disk is selected.
create partition primary
select partition 1
Comment: Run all these commands sequetially. The format command may take a while depending on the size of the drive.
Formatting the Drive in Windows XP (skip to “Make Drive Bootable” if this does not apply to you)
Windows xp has some issues with the above instructions. For whatever reason, many usb drives are not recognized as “disks” with diskpart.exe. Rather they are only “volumes” which can not be set to active primary partitions.
Right click the USB drive in Windows Explorer and click format. Format to NTFS if possible, if not then fat32 is fine.
We will use a special tool that you can download to fix the aformentioned problem. Download MBRWizard.
Go to a command prompt and navigate to the folder that contains mbrwizard.exe using the cd command.
Now run mbrwizard with the command:
Comment: This will list all disk, including usb drives. Take note of the number of the usb drive you wish to use.
mbrwiz /disk=a /active=a
Comment: a is the number of the usb drive obtained above.
Make Drive Bootable
Insert your CD/DVD or mount your iso containing your bootable Windows install. Open the command prompt again and use the “cd” command to navigate to the Windows install files.
cd /d F:\boot
Comment: This will change the directory to the drive labeled F and go to the boot folder. Use the appropriate letter for your case.
From the windows install boot folder, use the bootsect command to set the usb drive as bootable. The following example uses G as the drive letter of the usb drive
bootsect /nt60 G:
Comment: G is the letter of the usb drive.
Copy Installer Files
Now copy the entire contents of the windows install disk or iso to the flash drive(not the iso file itself, you will need to mount the iso or extract the files).
Set Bios to Boot from USB Drive
Go to the bios and change the boot order so that you boot from the usb drive first. Save and restart, and you are set! If you do not know how to do this, refer to your motherboard’s documentation.