Step by step tutorial.
(1)Get a USB drive at least 4GB in size
(2) Plug the USB into your computer
(3) Now go to Start Menu->run->cmd (Open Command Prompt) and Type following command
(4)Get the drive number by typing
list disk
Now identify your flash drive, for my machine it is drive 13.
(5) Now select the drive by typing:
select disk 13 and run the following commands
clean
create partition primary
select partition 1
active
format fs=fat32
assign
exit
(6)Insert your Windows7 DVD into the optical drive and check the drive letter of the DVD drive.
(7)Maximize the minimized Command Prompt in the 4th step.Type the following command now:
J:CD BOOT and hit enter.
Where “J” is your DVD drive letter.
(8)Type another command given below to update the USB drive with BOOTMGR compatible code.
BOOTSECT.EXE/NT60 H:
(9) Copy your Windows 7/Vista DVD contents to the USB flash drive.
xcopy j:*.* /s/e/f h:
J: drive is our mounted DVD drive and R: is our flash drive.
(8) Reboot the PC and go into the BIOS of your PC and set the first bootable device the USB drive.
(9) Install Windows 7.

