Yeah KDE 4 is a massive regression from 3.5.9 functionality-wise at the moment. Stick 3.5.9 on and set it as default and youll see far less crashing.
Got compiz-fusion working yet? Its the snazziest thing about Linux IMO.
I dont think KDE 4 will be feature/stability comparable until about 4.3, so well just have to wait. Its all style and no substance right now.