To make a bootable USB, first of all you have to install a software named “wintoflash”. You can download this software from the Internet.
1.So very first Install this software on your computer and then start this program.
2. It will show two different paths.
3.In first browse option you will select windows XP disk and in second browse option, select your Pen drive/USB.
4.Now Click next to proceed. It will copy all files of windows xp from CD to USB. Now click finish. It is complete.
Now you can use this USB for installation of windows. Enjoy.