I installed 2.1 over 2.0 without any probs. I put the boot image and the iso on the same usb stick. I have a $4 walmart usb hub (unpowered) and plug my logitech g15 keyboard + g5 mouse, hun in top usb connection, stick in bottom usb connection.
boots up, installs no problem.
I boot it up via the ethernet since the usb is SOOOOO SLOOOOOOOOOOOOOOOOOOOOW to boot the image.
yay for tftp on my linux box.