How can i make a bootbale USB?

plz tell me how can i make a bootable usb drive??? i hav 8Gb usb drive and i want to install windows using usb dirve plz help me. i dont want protable windows
Answer #1
you need a portable version of windows XP or vista. Just download it, follow the prompts for the program etc then reboot pc and go to the bios (pres delete on turning on the pc) and set the option so the usb hdd boots first
Answer #2
thanx mate m downloading Portbale Vista
Answer #3
sorry my mistake i mean portable