|Rufus will let you use DOS or an installation iso if that is any help. It will boot up as drive C:, moving your real hard drives to D:, E: etc. But you can work around this by moving the installation files to the real hard drives, making them bootable, power down, remove the USB drive and boot to real hard drives to continue the installation. You do NOT want the USB drive in the machine when you do this final step, it CAN take over and pooch the whole deal.|
Flash devices can never take the place of a real hard drive as they don't write or read at the same speed or use the same methods of doing that. You can do some pretty amazing stuff along these lines but I wouldn't trust it any further than I could throw it.