I have a windows 7 x64 system with Radeon HD4670. Grim Fandango complains about OpenGL functionality missing when starting. I tried everything I know, used the AMD searcher, Guru3D driver cleaner, and tried to install appropriate driver according to AMD but always with error messages. Also tried to put opengl.dll next to grimfandango.exe which helped people at steam apparently, but following the installation instructiosnfor opengl.dll at some site (fix4dll or some I guess) was unable to deregister and register opengl.dll, probably because of missing dependencies, sigh.
Gaming should be fun, this is not :-(