When trying to run 22.214.171.124 with todays libdrm on xserver 1.5.3 with kernel 126.96.36.199 I can only get a working KDE 4.2 beta environment with XAA or EXA (hmm, the latter seems to work while I write this, weird) enabled.
Chipset is Intel 852/855GM. With UXA I can get a plain xsession, run x11perf -aa10text or glxgears but kdm reboots the server constantly ending with a permanent system unavailability.
Created attachment 21294 [details]
Xorg server log
Created attachment 21295 [details]
UXA needs GEM kernel, i.e. 2.6.28 (or current -rc).