You cant go far wrong with a nikon.
Great lenses, good sturdy cameras too. Not used a d40 myself, but used to be pro in the 'olden days' before digital cameras (lol) and always used nikon (film) slr's - I still use them now and one of 'ems so old its almost antique - I got it 20 yrs ago, (2nd hand then) but it just goes on working and getting the shots!
Remember, its not the equipment, its the way you use it that counts - and practice makes perfect
I look forward to seeing your shots.