I had two K10Ds as well, but sold my backup body because I never needed it. My K10D has been my daily workhorse for six years and is still going strong.
Originally posted by clockwork247 it's because of the CCD sensor, in fact it probably has the pop at ISO 200 too, but it's only good until about ISO 400.
I have the same sensor in my sony A330, and I think a few nikon has it too, they were all made by sony.
Yes, that CCD sensor is the main reason I haven't upgraded bodies. ISO 200 works well, but I typically never go above 250. Take a look at any photo with blue skies taken by the newer cameras and one by the K10D. There will be no noise in the sky with the K10D.
The Nikon D80 had the same sensor as well.