Things are fine under Kubuntu 8.10. Window movement had been slow under Kwin, but is perfectly responsive under Compiz. However, I was hoping to improve the performance in some minor areas of Compiz (i.e., some minor jerkiness in the rendering of some window transitions). That hasn't happened. The one real problem is that asking the system to shut down often stalls out at a black screen.
Should I attribute all this to the current software landscape and figure the bugs will all be worked out in time? Or should I return this graphics card again while I still can?