How to boot/install Windows 7/Vista from USB Flash

Here is how you can create a bootable USB drive to install Windows 7 on your system.
1.Download Windows 7 BetaSave the file on your Desktop.

2.Format a 4GB USB thumb drive

My computer-->Removable disk(F)-->Right click and choose Format using the NTFS file system

3.Extract the Windows 7 ISO file 

• First Install WinRAR, 7zip will work too
• Right click on ISO file and choose “Extract to ” as shown in the above picture.
  
  
  4.Copy BootSect.exe

• Open the extracted folder and open the “boot” folder, inside which we’ll find a file called “bootsect.exe” that we’ll need to use.Copy the file (CTRL+C) and then open up “Computer” or “My Computer” and double-click your C: drive.We’re going to paste (CTRL+V) that “bootsect.exe” file right into C: so we can easily access it in a moment.
  
  
  5.Make the Drive Bootable
• Programs > Accessories and then right-click on Command Prompt and choose “Run as administrator.” 

• Inside cmd, type and enter the followings:
  
  1. cd\
  2. bootsect /nt60 f:
• We’re assuming the drive letter of your USB thumb drive is F:, so replace “f:” in the above phrase with whichever letter is assigned to your particular thumb drive. Hit enter and you should see: 

• The thumb drive auto-load when you boot up your computer.
  
  6.Copy the Windows 7 files to the thumb drive
• Now, copy all the files from the Windows 7 folder to the USB drive.
• Change the first boot device to your USB drive in the BIOS.
• Reboot the computer.You should be able to install Windows 7 from your USB flash drive now.