Have you tried plugging the iPod in with a different USB sync cable to verify the issue is not with the cable? It might not also hurt to connect it to another USB port as well.
Otherwise, try manually placing the iPod into Disk Mode and then connecting it to your PC.
I've seen this discussion with all sorts of solutions offered. But before you go to extremes, are you plugging into the computer DIRECTLY or a hub, keyboard, or any other peripheral? I was having the same problem while plugged into a hub, but plugged my iPod directly into my Mac and, voila! Too bad there is no message when you plug an ipod into a device that has inadequate juice for it, since it would save a lot of time!