Just setup test-PCLinuxOS-KDE4-2011.6 on an older Athlon 2500 with ATI-9600
Only setup problems with the ATI
/etc/modprobe.preload, added radeon
etc/modprobe.conf, added options radeon modeset=1
now the right driver is loaded as explained in the start of this topic, still no 3D
etc/X11/xorg.conf, added Load "dri" in Section "Module"
Load "v4l" # Video for Linux
now I've got Desktop Effects
(not all but...)
Succes with your experiments.