RE: Nikon D40X SLR or Cannon EOS Rebel XTi?????
Yes, the D80 is a step up from the D40 but for an entry-level DSLR you can't go wrong with it. I picked one up a few months ago before my trip to Alasaka and I LOVE it. I opted for the 6.1 MP D40 over the 10.1 MP D40x simply because of the price difference. A lot of people think more megapixels = better photo, which isn't always the case. And unless you plan on blowing up your photography to poster-sized prints 10 MP is overkill. Most people are using photos for the web and e-mail, which means they get resized from 5000 pixels wide down to 640 or 800 pixels wide. The D80 is also quite a bit larger and heavier, making it more of a pain in the butt to carry around. I tote mine in my pack when I'm hunting a lot, which was another factor in my decision.
Again, you have more lens options with the D80 but in the future more and more companies are going to be producing AF-S lenses to fit the D40s and future cameras of the sort, so your options will be increasing. And again, for entry-level photography most people are fine with the 18-55 mm lens that comes with the camera kit. I personally justed picked up a Sigma 55-200 to give me a little bit more range for $150 and have also been happy with that as well. Down the road when I want to get more advanced I may pick up a D80 body and a good F2.8 lens, but for now that combo I have works great for what I'm doing, which is the same as the majority of people - family functions, parties, friends, some scenery/landscape photos, etc. Basic stuff for the most part.
In any case, I did all the price comparisons between the Nikon and Canon, read all the reviews, held them in my hand, and ultimately decided on the Nikon. So far, so good.