I have found that most of the problems with nVidia drivers come from the 8800 series. My 7900 was running fine in vista, the trouble started when I upgraded.
I believe the SLi drivers came out on like feb 1st or something. I think they were the day after the first 8800 drivers were released.
The first ones released like a day after vista was out only had single gpu support, and they promised to put out sli drivers the next day, which they did.