Download "wakepup" which is a program for booting puppy linux.
Click on Wakepup an you should be prompted for a formated disk etc..
Go into the disk you just made and delete everything in...

The reason i wanted to boot from usb was because at the time i didn't have any cd around and wanted to run backtrack

i had the same problem, what i did is make a dos boot disk an include my usb dos drivers(USBASPI.SYS,ASPIDISK.SYS) then i added a line in my autoexec.bat so it ran bt/boot/dos/loadlin or you could...