Well since replying to this thread I have now come upon my first two problems with USB devices ever!
Took my own external Hd in to University to nick gigs rather than megs worth and was a little perturbed to find that my external enclosure just say there and made meeping noises. Didn't show up on the list of cool heath robinson devices on explorer etc.
After a quarter of an hour swearing at Bill Gates I plugged the other USB splitty whatsit into the second USB port and bobs your uncle.
Only problem now is that the sprog's new computer's USB ports just sit their laughing at me.
It dosn't rain but it pours.
P.S. I'd really recommend external enclosures.... You can get a 20 gig 2.5" HD for £20 or so and the enclosures are only £5-10. Compare that to these fiddly USB pens which are nowhere near as cool, hold far less and don't even look slightly like James Bond's cigarette case. Even worse they seem to be designed to be slightly too small to hold really dodgy Japanese porn.