Attached is the Current Accel drivers and bundles from 10.5.5, and the old Fixed IntelIntagratedFrameBuffer.kext
as well as Callistohal, and Callisto's FB, is seems that when modding the GA.plugin as suggested in other threads for ATI cards, and using Callisto_B006 I can get Full CI/QE performance even though the System profiler says it's software not hardware Accel, the X bench scores are Better then when it was mouse tearing.
here is the Files to try, after a bit, I'll edit this to include links to the posts I am talking about, they are on my home Hack.
Links to the ATI forms that helped get CallistoFB working with the GMA950 Drivers
this is currently configured for the 27A2 Displays, and gives full Acceleration without Any artifacts or mouse tearing with both internal and external video working.
Cheers and here is hoping that this Helps others.