NVIDIA 9500 GT - Macbook pro and opengl

One of our customers is having a graphical problem with their Windows 7 basic 32 installation on a MacPro 2009 running a NVIDIA 9500 GT. Their listed driver is GeForce 331.65, which correlates to the results of a dxdiag report, but a printed vendor/version/extensions opengl report contains just the following:

Vendor: Microsoft Corporation
Renderer: GDI Generic
Version: 1.1.0

…which is as if the graphics card isn’t found by opengl at all. Has anyone got any clues or ideas about what could be the problem here?

Kind Regards,