400D is entry level.

pros of d40x over 400d

-better noise performace
-better awb
-better color reproduction(this is fairly objective)
-sd card?

cons

-no af with non af-s lenses..which means it shuts u out from some cheap good 3rd party lenses..
-less af points.

hard to say, there's no right and wrong here. if u understand technical jargons, reading reviews will help you alot. also, try out the cam before buying it. feel it, touch it, play with it and find out which suits you more.

also,ask yourself,

why do u want a dslr? (u said portraits and landscapes)

then i suggest u go for body only and get a 50mm with another wide angle lens. true u, will not have autofocus for 50mm in d40x but it's not tht hard to learn manual focus.

how for are you willing to upgrade?

will u still be using the camera years from now? if yes, the system does matter.

i can't make a conclusion only you yourself can make cheers, hope it helps.

nope,d40/40x only supports auto focus with af-s lenses. other than that, it's manual focus with G,D type lenses.

i got it out from a japanese magazine. even if not better, it's definitely on par.

as i read, it compared with both nr on and off and both beats the 400d, so i would say everything is marginal. the d40 n d40x only lost to 5d

i'm just talking about noise performance la, nothing else.

more like the 400d underexposes? and why is there a saturation +1 in the settings? not a really fair comparison. tht said, i still prefer the colors on the d40.

but when u look at the pic 400d with +0.7EV still looks under while d40 at +0ev is ok. if the d40 would be +0.7ev, it would overexpose, while 400d would underexpose at +0

u dun need dof preview unless you're doing macro. u rarely use it in portrait.