Even the manufacturer's site can give problems. My system is a 10 month old Vista Home Premium 64-bt
I bought it brand new. About 6 months ago (with the usual recommended updates) one of the optional ones was nVidia update for just my system. I downloaded and installed and ended up with no display at all. Had to force a reboot in safe mode and did a system restore. About a month ago it was again included in the latest updates (or possibly a later version). I forgot what happened - didn't I?

. Lo and behold same problem. Keep meaning to ask nVidia about it but forgot that too.