Affine Transformations

Why write your own scaling/rotation engine when the hardware has one built in?
I've been slugging through
Patater's DS Programming Tutorial. It covers the concept pretty well, though I think his code is a bit too complex just to show off the basic features of the handheld. On the other hand, it sets you up for much more advanced programming, so I can't really complain.
Work is underway to better understand the Nintendo DS and move some of my game programming endeavors over. This time I'll try a more direct approach, since the hardware takes care of a lot of the organization; I don't have to write a general purpose engine before I can get to the fun stuff.
I have Spring Break before me, too, and I've declared it a week of DS programming. Here's hoping I can keep myself on track!
Edit: WOW YOU CAN TOTALLY SEE ME REFLECTED IN THE DS