I know many have seen this before but with netbooks on the rise and the fact that they don't have cdroms built in this is becoming more and more common. My reason for needing it was actually my cdrom wouldn't read my windows 7 dvd.
Anyways if you need a really simple way to do this simply goto http://wintoflash.com/download/en/ and download this application. All you have to do is insert a flash drive into a computer and put Windows 7 in the cdrom or mount it using one of many tools to mount an iso as a cdrom. Then tell wintoflash where the cdrom is and where the flash drive is and press create. Takes about 15minutes and you have a flash drive that can install Windows 7 on a computer without a cdrom.