Neowin reports that Nvidia Foreware 87.15 Vista Drivers Released for Windows Vista February CTP build 5308 have been released. It is only 4MB in size and doesn’t contain the control panel. Users are reporting that this driver is still slower and buggy than than Microsoft’s own driver and has serious performance issues even with 7800gtx and AMD 4000+.

So the bottomline is do not upgrade to these drivers yet.

From Neowin Forums