Originally posted by Abstract Hmm I would disagree, The K-x and K20D are in two different categories, only thing the K-x would be better for is high ISO shooting. K-x is a beginner model, the K20D is a enthusiast/semi-pro model. Up to what you are looking for though.
Well, AF is better in K-x than in K20D. Even K-m is better (check two movies in this Korean site):
Pentax K-m vs. K20D
Additionally, sizes of these bodies are completely different (I prefer smaller bodies, so I have chosen K-x) and K20D is heavier (so if you like hiking or climbing it may be a problem).