As for lenses I looked a lot and read reviews at photozone.de. From shooting with friends' cameras (and at work a lot with the 20D), I really like wide lenses! And both Nikon's and Canon's are expensive (500+ Euro for a Canon 17-85 4-5.6 IS) and even if it's not 17mm, 18mm for example, I'm not fond of getting a Canon 18-55 lens that comes with the Digital Rebels! And I'm not really that pretentious for now about any specific lenses.
If you get a Sigma 18-50 mm f/2.8, or Tamron 17-50 mm f/2.8 lens for either Canon or Nikon, it'll be quite wide, but also quite good. Either that, or a Tokina 12-24 mm f/4 lens. The Tokina is much wider than either of the other 2 lenses I mentioned, but it obviously doesn't give you a lot of reach on the long end.
Also, an "18 mm" lens, for example, is actually wider on a Nikon D80 than on a Canon 40D. Same with all equal focal lengths. It won't matter by much, but it's something to remember.
Handle the Canon 40D. It's supposed to be a good camera, and it definitely takes nice photos. I don't personally like the way any Canon DSLR feels. I hate that jog wheel. However, you may love it, or you may feel that the difference between them (ie: ergonomics, size, weight, price) is very small, and in that case, get the Canon 40D.
I still say get the Nikon D80 because I personally prefer Nikon camera bodies, and it comes with the 18-135 mm for the same price as a Canon 40D with the 18-55 mm kit lens. However, the choice is yours, really.