http://www.imaging-resource.com/IMCOMP/COMPS01.HTM
You can select any two cameras and compare test shots. It will list the K100D if you select "all" instead of just "current."
You can also poke around
www.pentaxforums.com.
I can shoot some high ISO stuff with my K10D if you don't find what you like on that first site, but I'd guess the more controlled settings there would be a more fair comparison.