NVIDIA just released a new WHQL (Microsoft certified) driver for their GeForce series graphics cards. Any GeForce card to date starting from series 6 and upwards seems to be supported.

• WHQL-certified driver for GeForce 6, 7, 8, and 9 series GPUs.
• Improved 3D performance and load times for GeForce 8 and 9 series GPUs in some DirectX 9 and OpenGL applications as a result an improved shader optimizer.
• Supports single GPU and NVIDIA SLI technology* on DirectX 9 and OpenGL.
• Several game and application compatibility fixes. Please read the release notes for more information on product support, features, driver fixes and known compatibility issues. .

Note: Quad SLI technology with GeForce 9800 GX2, 3-way SLI technology, and Hybrid SLI technology are only supported on Windows Vista.

We have a discussion thread open on these drivers right here

Have you read the Guru3D SLI (3-way and 2-way) review ?