Note: This method will create a USB drive that is bootable. You can then copy the contents of an operating installation disc onto the drive to create a portable installation drive.This method only works in Windows Vista, 7, and 8.
Step 1: Type cmd in start button. Right-click on it and select Run as Administrator.
Step 2: Enter the command diskpart and press Enter.
Step 3: Type the command list disk and press Enter. Make note of the number next to your USB drive.
Step 4: Enter the command select disk #, replace “#” with the number from the previous step and press Enter.
Step 5: Enter the command clean and press Enter.
Step 6: Enter the command create partition primary and press Enter.
Step 7: Enter the command select partition 1 and press Enter.
Step 8: Input the command format fs=ntfs and press Enter.
Step 9: Enter the command assign and press Enter.
Step 10: Type exit and press Enter to end the disk management program.
Thats it, you have done it like a genius !!!
Now you can simply drag and drop or copy and paste the Operating sysytem files to the pendrive or USB drive.