Originally posted by paperbag846 The only lenses that will AF with the D3100 will be ones with the motor in the lens (more expensive lenses).
The feature set of the K-x is more complete... but more importantly, what kind of photography do you want to be doing? Pentax and Nikon each have their own strengths, and if you are going to be investing in lenses, THAT should dictate which body you buy. Your future self will thank you.
I am new to all this so please forgive me. I thought you could get the same lens pretty much from any of the major players? I want to do all round photography at the start as i haven't found one particular genre that I really like yet. I am looking for an all round camera with video as well.