Hi Jon -
I went out and bought a self-powered usb hub today. It looks like all self-powered usb hubs also have the capability to draw power from the usb port under 500ma and then use the external power supply if over that. I'm not sure if there is a way to ensure that this hub is drawing its power from the external supply rather than the usb port. If there is a way please let me know. As it is now this doesn't seem to have made any difference.
Thanks,
Pat