How can you boot off an external hard drive? (USB)
 

Anyone know?

My cdrom is broken and i have my windows xp iso with me only.. I gotta do a fresh install

Change the boot sequence in your BIOS setup menu.

Start with your foot in a slightly posterior position, then drop the hard drive from about shoulder height. While the hard drive is falling quickly move your foot in an anterior and slightly superior motion so as to intersect the hard drive. The application of coordinated timing will greatly increase the chances of successfully booting your hard drive.

most modern motherboards have the ability to "boot from usb" and it will pull from whatever usb device is connected that is a bootable drive

Bet you trained at Dell?

Correct. An old one won't though. Check the BIOS fosheezy

You are not gonna have a lot of luck booting from an ISO; even if you write it to the beginning sector of the disk, it's not likely to take that. The ISO/DVD images have a 'floppy image' at the beginning of them.

Start here, good luck!