When I use Konq 3.5.10 and Konq 4.0.4 (OpenSUSE 11.0) I get very
different results with Acid3. Are there major differences between KHTML
version 3 and 4, or could it be due to settings?

I would like to be able to choose webkit as rendering engine in Konq 4,
how can I do this? I have installed kde4-webkitpart, but see no
difference in rendering of Acid3 before and after install. I haven't
figured out how to check which rendering engine is used.