If MS tool doesn't work try: USB Windows 7 Installation Key Drive - Create
Ultra ISO Bootable tab shown earlier in thread.
These are the simplest and most reliable. One of these will always work, but sometimes it takes trying others first.
When I first got my Kingston Data Traveler tool stick, I could format Primary, copy over install files into stick and it would boot if I spilled the files out of folder into root, even with other tools on it. Now, however, it requires writing it to stick using UltraISO to apply bootsecting. So this is a changeable process.