K100D seems to be the better camera.I plan to use the camera to take my family, vacation and possibly creative shots for competition.....
Putting aside the price, which is a better camera? And why?
cheers.
The main issue is with lens compatibilty. Nikon D40 only autofocuses with AF-S lenses, with the few AF-S primes being 200mm and above. All other AF lenses, including Nikon primes, 50mm, third party lens (except Sigma HSM) will become manual focus. Older manual focus lens will not meter on Nikon.
Pentax K100D will autofocus with all AF lens and meters with manual focus lens. K100D has depth-of-field preview which D40 doesn't. In body SR on K100D will be useful on stationary objects, which requires expensive separate lens purchase for Nikon.
If choosing Nikon, I would rather go for just discontinued D50 or second hand D70/D70s, as they don't have AF restriction. Their viewfinders are quite small though. The Nikon 18-70mm would be a good choice for kit lens, better image quality than 18-55 or 18-135.