Hi, personally there is no 'bad' dslrs on the market (that I know of). I believe the D40 is one that will only take the nikon equivalent to sdm lenses?? if so that is probably the only dslr I would avoid at the moment (why limit yourself when you dont have to). I believe the k10 / k10d cannot be beat for value for money for camera and as mentioned the lenses are excellent, however the pentax system is extremely lacking at present for long glass.
As they are all pretty good, dont over analyse, just go into a good camera store and ask to try them. Play around (in store), see how they feel, look at the menus, look through viewfinder, which camera makes you want to go an take photos? (i had decided on a 350d until I tried in store and hated it the feel of it, and got the Ds instead and just loved using it, same for k100, but my wife with small really doesn't like the k10 and wont use it (I aint complaining
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Phil