You're right, the monitor hub does not seem to be powered, I had assumed that it would be.
I don't have a powered USB2 hub to test your theory... but, just to get this straight, you are saying that ALL my USB2 devices (that's 6 memory sticks and 2 HDs) draw too much power for an Optiplex 380 and that therefore they will ONLY work in this machine via a USB2 powered hub?
That seems very hard to believe since they ALL work perfectly in ALL my other machines...