How to make BOOTABLE FLASH drive

we know how to install the OS from a CD. But when it comes to install the OS from a pen drive so many think that an extra software is needed. But there are some ways where we can install the OS from a pen drive and that too without using the additional software ( just by using command prompt). Here is how we can do that. Enjoy..... :-)

1) Save all data on your flash drive to another location if you want to keep it.
  2) Insert the flash drive into a USB port on your computer.

3) Click the Windows "Start” menu, type “cmd” in the Search field and press “Enter.” This will bring up the Command Prompt. Type “diskpart” and press “Enter.” The Diskpart window will open.

4) Type “list disk” and press “Enter.” In the listed disk drives, find the flash drive. You will be able to recognize it by its listed size. Type “select diskname”, where diskname is the name of your disk. Click “Enter.”

5) Type “clean” and press “Enter.” This will remove everything on the drive.

6) Create a partition by typing “create partition primary” and pressing “Enter.” Type “select partition 1” and press “Enter.” Type “active” and press “Enter.”

7) Type “format fs=fat32 quick” and press “Enter.” This will format the drive.

8) Type “assign” and press “Enter.” This will assign a letter to the flash drive, such as “G.”

9) Type “exit” and press "Enter."

10) Insert the Windows 7/Vista installation disc and note down the “drive letter” of your DVD drive. ex: “H:”.

Open the Command prompt. If you are using Windows 7/Vista then open it with administrator rights*.
* Goto Start -> All Programs -> Accessories -> Right-click on “Command Prompt” and select “Run as Administrator”.

Now type the following list of commands as shown below:
H:
CD BOOT
BOOTSECT.EXE /NT60 G:(NOTE:
G: is your USB drive letter)

That's it. Now you can install the OS directly from the pendrive.