Maybe I'm revealing my own ignorance about the issues, but I found christiaan's remarks to be a little unclear, so I'll restate it a little bit... straighten me out if I'm wrong here.
USB 2.x is backward-compatible with USB 1.x. That is, an older USB 1.x device can be successfully plugged into a USB 2.x port -- the new interface recognizes the old device.
I'm not sure it's true that a USB 2.x peripheral can be plugged in to a USB 1.x interface successfully. First off, why would the new device be a USB 2.x device unless it was benefitting from the additional bandwith? It would be pointless for a company to redesign an existing product to communicate via USB 2.x when (1) any USB interface, 1.x or 2.x, will recognize it anyway, and (2) the device makes no use of the improvements inherent in USB 2.x. (I wouldn't want to buy a device made by a company that would make such a bad cost/benefit decision.)
Therefore you can assume pretty much any USB 2.x compliant device would be using the increased bandwidth to work properly, and therefore would not work successfully plugged into a USB 1.x interface.
So the statement "No you don't have to upgrade to use USB2.0 gear unless you want to take advantage of the higher bandwith of USB2.0" is kind of senseless, because there wouldn't be a USB 2.x device that did not depend on higher bandwidth for its operation, and if you wanted the device to work the way it's supposed to you would need a USB 2.x port -- meaning you would need to upgrade to use USB 2.x.