From my experience with a Toshiba M400 with GMA950 running Kalyway 10.5.2 and a successful update to 10.5.3 using Netkas method, I can tell you that the only extensions I had to replace with old ones for the blue screen problem were AppleIntegratedFramebuffer, IOGraphicsFamily and IONDRVSupport. None of the GMA950 extensions were touched by the upgrade.
Before you rebuild your system, try connecting an external monitor to see whether you can access the GUI. Alternatively you can boot with -s switch and recover your previous kexts from the backup folder via command line (I know, tedious but there's plenty of help in the forum).
If this doesn't work I can help you with making a working IntegratedFrameBuffer .