[yusuf]

Sony's CCD sensors have been well known for their superior low ISO DR. Not sure about comparing ISO 200 between the K10D, K20D and K-x, but ISO 100 is definitely won by the K10D.

hmm, but k-x is Sony and K20D/K7 is Samsung, isn't?

you can use two bodies k20 or k10 with your sigma 10-20
it is mach easier to make hdr photography's with this bodies
k7 is good for tele lenses for sport photography

Can you explain this please. Why k20 would be better than k7 for HDR and why k7 for sports?

[jolepp]

I would have two k-x bodies to have exactly same controls (the k-r is very similar to the k-x so that might be good too?).

[Ira]

Unless you're talking about in camera HDR, which is a joke an

[Steve Beswick]

hmm, but k-x is Sony and K20D/K7 is Samsung, isn't?

The k-x has a CMOS sensor, like every Pentax over 10 megapixels. The K10d has a Sony CCD sensor. It is a totally different beast.