i got my d40 few months ago and its a blast, you can read all the reviews you want, but go to a store that has both the nikon d40 and the canon and see which one feels better in your hands, i have point and shoot canons and love them, but this d40 feels better to me then the canon did,just a personal preference. its light to carry on hikes and slap on a polarized filter on it and the outdoors photos are incredible, as for the 6MP don't worry about it unless u plan on doing billboards.
as for taking pix of the tank which I'm guessing u plan on doing the kit lense 18-55 is ok, not the best, it will do at first. i just picked up a 50mm lense for another 50$ (used) and its unbelievable!!!
just my opinion, hope it helps...