Thanks for the info everyone. This doesn't sound like quite the disaster I was afraid of. I'll try to drop by the shop one day during the week and see what they have to say. I've gotten about two years of good service out of her so I guess I shouldn't be surprised that she's starting to show a bit of wear.
Bugman - I had intended to replace the spokes (I'm missing three and found a forth one freshly broken), but unfortunately they're on the side of the wheel facing the sprocket gears and I don't have a tool for removing them.
One other question. Is there a good basic 'Bike Repair For Dummies' type book you guys can recommend? I can do the simple stuff like change a tube and tighten the rake cables, but major work like disasembling the gears and replacing bearings are a pretty frightening concept.