How to install operating system in USB Pen drive?

Step 1. Format the USB Flash Disk

Run CMD (elevated) and type:

1. diskpart
2. list disk (*now find your USB disk number, youll find it by its size)
3. select disk 1 (*if your USB is disk 1)
4. clean
5. create partition primary
6. select partition 1 (*this is 1, no matter what number is your USB disk)
7. active
8. format fs=fat32 (or ntfs, works with both)
9. assign
10. exit

Note: Don't type the things in parentheses above!!

Step 2. Copy Windows 7 or Vistas DVD content to the Flash Disk

Still on CMD, assuming your dvd is drive d: and your usb is drive e:

* xcopy d:*.* /s/e/f e:

Your done. Works perfectly.You'll make the fastest install ever.

First create usb bootable to pen drive, then select first boot device (usb device) from bios