Nvidia's first release Vista drivers were simply incomparable to the performance of drivers for Windows XP. PC Perspective interviewed Nvidia's Software Engineering VP Dwight Diercks and finally asked what was on every Nvidia user's mind.
Diercks explained that with Windows XP, NVIDIA simply needed to create two separate drivers: one for DirectX rendering and one for OpenGL rendering, while for Vista, NVIDIA has to develop six separate drivers: SLI and non-SLI versions for DirectX 9, DirectX 10, and OpenGL. In Vista, Microsoft moved the driver stack into the user space in the operating system, effectively making the kernel much more stable, but adding another layer of abstraction for NVIDIA's software to get through before directly accessing the hardware. Each Vista driver supposedly contains 20 million lines of code (roughly the same number of lines as Windows NT 4.0).
Diercks has said that the new ForceWare drivers will be release on a monthly schedule, much like AMD's Catalyst drivers, unless of course there are major bugs found between releases. A WHQL-certified ForceWare release for Windows Vista is expected before the end of February. Nvidia also plans to release another update in March with GeForce 7 SLI capabilities and better TV output support. April is the month where support for DirectX 10 SLI and H.264 video acceleration is planned to be addressed.