I installed Ubuntu on a USB drive following these instructions: http://www.howtogeek.com/howto/linux/create-a-bootable-ubuntu-usb-flash-drive-the-easy-way/
When I go to boot menu the USB drive does not show up. I also downloaded Make Bootable Device from: http://www.megaleecher.net/Make_Bootable_USB and my USB drive is not select-able from this program either.
I am running Windows 7 on a 64 bit machine.