I noticed in your xorg.conf you have 3 device sections 1 for the vesa driver, 1 for nvidia and 1 for fglrx... any reason in particular you need vesa ? Also are you trying to run both an Ati and a nvidia card in the same rig ?
Like pete910 above I'm on Mandriva, 2010.1 Rc3 64 bit to be precise,
and I've had no issue enabling kwin on kde 4.4.3 with the cat 10.4-10.6 drivers.
His ServerLayout section is only using a single screen tied to the fglrx driver. There's no harm in having extra Device sections if they aren't being used.