Just to give you an idea, it took me on my USB2 external HD to transfer a couple of HD backups (connected to USB1 interface) around 2 hours. Now the same transfer on a USB2 Interface took me only 20 minutes! THats a huge difference, it would be faster with firewire 800 of course, but i dont have that!
It a very worthy difference, and very noticible
~PCTech