quote from:
http://www.ehow.com/how_5942169_convert-bootable-iso-bootable-usb.html
1
Insert your USB drive into the USB slot in your computer. Open a command prompt window by going through the “Start” menu and searching for “command prompt.” Type “diskpart” into command prompt and press “Enter.” Enter in “list disk” and see what disk number your USB flash drive is. Enter in “select disk #” with # being the disk number of your USB drive. If your USB is disk 3, you would enter in “select disk 3.” Type in “clean” and your USB drive will be erased.
2
Type in “create partition primary” followed by “select partition 1.” Type in “active” and then “format fs=fat32.\" Finally enter in “assign” and type in “exit.” Your USB is now ready to have the ISO put onto it. Copy and paste your bootable ISO file into your USB flash drive. Alternatively, you can mount the ISO file as a virtual drive with Daemon Tools, which is available in the resource section of this guide. Once mounted, open a new command prompt window and enter in “xcopy d:\\*.* /s/e/f e:\\.” The drive letter “d” is the mounted ISO drive and the drive letter “e” is the USB drive. If your ISO is drive X and USB is Y, the command will be “xcopy x:\\*.* /s/e/f y:\\.”
3
Reboot your computer and enter into the BIOS settings by pressing the “F2” button when you see your computer manufacturer’s name. Go to “Boot Options,” and set your USB drive as 1st priority. Press the “F10” button to save your settings, and your computer will reboot from the USB drive.