Thanks for all the great advice! I went to my LBS to buy the tools, and the guy ended up changing it for me as he showed me how to do it, but it really did seem easy. I was glad he showed me though, cuz the tricky part was lining up the cogs correctly and it was just easier for him to show me than tell me. I put the wheel on, and it shifts smoothly without any derailleur adjustments. I think I'll take apart a really old wheel to practice on this weekend, to be sure I will remember what to do when I have to do it again.