D40 is a very good camera, I use a D50 which is still giving me fantastic images and I've not yet contemplated upgrading, only will when I have enough money for a D300!!!

Try going to Jessops in town and getting one in your hands, compare different bodies because at the endof the day you have to be comfortable with th camera, and some are better than others.

My Nikon felt alot mroe comfy compared to a Canon I sampled...

Good luck!