Though I have Canon equipment, if I were to start today, I'd probably buy the Nikon D80. There is one thing that I run into all the time that annoys me more than anything. Highlights and shadows. The D-Lighting feature in the D80 would put it over the XTi for me. I know there are remedies to solve that like shooting in raw and photoshopping, but if the camera can do it automatically, it'll save me a ton of time.
The whole vibrating dust-be-gone thing doesn't appeal to me much. It took me 2 years in ownership before I had to clean my sensor on my current Canon, and I did it myself after much reading and buying a kit that cost less than $30 shipped.
If you haven't done so already, read about and see samples of D-Lighting in this article below...
http://www.dpreview.com/reviews/nikond80/
Good luck!