To elaborate, there is no open source 3D drivers for NVidia, they are an uncooperative company.. no documentation for others to develop drivers either.
@DrJ, the opposite of direct rendering is "indirect" rendering... all 3D (i.e OpenGL) is unaccelerated.
I recommend using ATI/AMD cards, they have documentation available.. but don't get the newest one out there.. takes time to write drivers.
Another option is getting the proprietary
bl
ob driver from NVidia, but this is not recommended.. go get a refund.