NVIDIA has released ForceWare 158.24 beta drivers for use with Windows Vista.

Release Highlights:

-This driver fixes a problem when trying to enable NVIDIA SLI using the international versions of Windows Vista.
-Increased performance in 3D applications.
-PureVideo HD support.
-Add support for forcing Vertical Sync in DirectX applications.
-Updated NVIDIA Control Panel with improved user interface (Please see the Release Notes for more details).
-Numerous game and application compatibility fixes.
-This driver supports the following 3D features:
-Single GPU support
-DirectX 9 support for GeForce 6/7/8 series GPUs
-DirectX 10 support for GeForce 8 series GPUs
-OpenGL support for GeForce 6/7/8 series GPUs
-NVIDIA SLI support
-DirectX 9 support for 6/7/8 series GPUs
-OpenGL support for 6/7/8 series GPUs
-DirectX 10 NVIDIA SLI support for GeForce 8 series GPUs will be available in a future driver
-Please read the release notes for more information on product support, feature limitations, and known compatibility issues

Release notes (.pdf format)

Vista 32-bit | Vista 64-bit

NVIDIA homepage