Todd,
I have the older, Canon Digital Rebel XT. The current version of the camera is XTi which has higher resolution and some more features. Mine camera ran out of batteries pretty quickly on Sunday and Larry Gill was nice enough to lend me his Nikon D40. Thanks Larry.

I'm not trying to be politically correct but I like both cameras. The biggest difference to me was that the Nikon seemed more solid than the Canon. It was a little bit heavier and it seemed a little bit more "put together".
Personally, I think the controls on the Canon are a bit more intuitive. I remember when I first bought it I was able to use it right away and never really had to figure anything out or read the manual. I'm lazy like that so that was really nice. There were a couple of controls on the Nikon that I couldn't figure out and I was left with the impression that the Nikon seemed a little harder to operate.
I've heard that the Nikon has more features than the Canon but that's not a big concern of mine because I don't know how to use the features I have on the Canon yet. I leave it in default autofocus setting 95% of the time. I'm sure not sure if any of that is a big deal because you would probably get use to the camera and it's setting after using it for a short period of time.
One thing I noticed is that I didn't have to use the flash on the Nikon while I did for my Canon, hence draining my battery. It could be that the Nikon is better at letting in? It could be that Larry had set up his camera properly while I didn't? I don't know. Both cameras were using the default autofocus. Nathan's kohaku was taken with my Canon (with flash). Dai's kohaku and showa was taken with Larry's Nikon (without flash).
-Dan