My bad i thought i read Internal HDD. Nevermind my comment, im not to sure then about booting an external dvd drive because ive only worked with USB external dvd drives for booting a dvd. Because i know for a fact USB is plug in play which means you dont need a driver and it can boot straight off it. Firewire might not have that im not sure at least for your motherboard.
Do you have a flash drive thats more than 4 gigs? If you do you can put windows 7 on it and boot the install straight off the flash drive with either the microsoft utility or win2flash.