To Create Bootable Win XP/ Win 7/ Win Vista USB Drive in following steps.
USB atleast of 2GB capacity
ISO of of your required OS(xp/7/vista)
10 minutes of your precious time.
A simple APP called WinToFlash tool (free) which you can download from here.
1) Insert your pen drive and back up your files and folders as it will be formatted during the procedure.
2) Now execute WinToFlash tool.
3) Now follow the on screen instructions and browse to your Windows 7, Vista, or XP ISO files.
4) Now make sure your pen drive letter is correct.
5)The final step – Now press “create” button and wait for few minuets to get your bootable USB stick.
That’s it your are all set and done. From now you can boot XP/7/VISTA from your USB drive.