I don't know anything about cameras but I work with a guy that is a camera nut and he swears the Canon 40D is the best camera ever made. And from some of his pictures I would have to agree.
I'm in the market for a new camera also, and have been reading a little bit on DSLRs. The 40D is about $1300 but from what I've read (and its widely talked about in astrophotography forums) its easy to use because of its "live view" feature. I guess I'd have to see it to know it, but it supposedly makes focusing easier when you're using your camera at the telescope, and focusing is definitely one of my weak points.
If I wasn't planning on doing astrophotography with it I'd consider the XT. Certainly not as expensive as the 40D.