Mac, I read this thread quickly. Congrats on purchasing the Canon. I think you'll be pleased. If you can sit fairly close to the front at school events (stages), you might like to purchase a 50/1.8 lens. That, along with setting your ISO from between 400-800, should allow you to get some nice shots without needing a flash.
I started with the Rebel xti, went to the Canon 40D and now have those plus a Canon 1DIII. They're all 2007 models and have approximately 10 mega pixels. That number is not your guide to quality. so don't worry about it. I've been moving along that range as my photography moved towards a lot of hockey and I needed a camera with a fast frame per second rate (40D) and then one with higher ISO (1DIII). The Rebel was purchased new with the help of gift certificates, the 40D was purchased used through Ebay (and has since had the shutter replaced) and the 1DIII was purchased, new, but five years old for a fifth of what it would have cost when it was first released. You can have a lot of fun with your photography even if on a budget
Myra