NVIDIA has a new driver ready and waiting for you guys. It's build revision 180.84 and comes in beta form. According to our forum thread on this driver is has several improvements for Grand Theft Auto 4. If you give these a try, let us know how they work out.
The drivers come with the PhysX 8.10.13 system software as well.
Download:
GeForce Forceware 180.84 Windows XP 64-bit
GeForce Forceware 180.84 Windows Vista 64-bit
GeForce Forceware 180.84 Windows Vista 32-bit
GeForce Forceware 180.84 Windows XP 32-bit