How to boot Asus EeePC 1005px from USB drive
During the BIOS boot-up screen, press ESC button and you will be presented with a boot device menu. Select the USB drive that you have already plugged in to your netbook and press enter. The boot device you selected is temporary and it's good for the purpose of reinstalling OS into the netbook. You don't have to change the boot order from the BIOS setup as the change is going to be permanent. By using the boot device selection menu, you can temporary set the boot device for that boot up only.