That would be waterzone.zip. Look for it at this site or else on Avsim.com. You could also go for morewatr.zip which looks about the same and is also very good.
It requires a card that is DX8 capable and unfortunately yours isn't fully DX8 capable. By this I mean you cannot turn on the water reflections. You can still load the new textures and it should look better however.
I have the same card. Try updating the drivers. They say that they make the card DX9 compatible? Driver version 66.93. It's in the driver downloads section of the NVIDIA site.
Any insite into these updated drivers? Has anyone used them?