Depending on what Nvidia device you check in device manager you can get very different driver versions. The read me in my Nvidia chip-set driver package lists the following:
This Win7/WinVista 64-bit nForce UDA driver package for MCP61, MCP72, MCP73, MCP78, and MCP7A consists of the following components:
Ethernet Driver (v73.30) WHQL
Network Management Tools (v73.25) "Sedona"
SATAIDE Driver (v11.1.0.43) WHQL
SATARAID Driver (v11.1.0.43) WHQL
RAIDTOOL Application (v11.1.0.43) WHQL
SMBUS Driver (v4.79) WHQL
SMU Driver (v2.08) WHQL
GPU Driver (v197.13) WHQL
PhysX (v9.10.0129)
Away Mode Driver (v6.0.6000.115) WHQL
Installer (v8.36)
Acording to ASUS this is NVIDIA nForce Chipset Package Driver V15.56 (lan driver version V73.3.0.0) for Windows Vista/Windows7 64bit.(WHQL)
On the Nvidia web site, in the Download drivers section there is an
Option 2: Automatically find drivers for my NVIDIA products.
It's never worked very well for me but you might have better luck.
It should at least tell you what version is currently installed.
I prefer to get my chip-set driver from motherboard manufacturer. They sometimes modify the stock drivers to match something they have done to the motherboard. I think this is why the Nvidia tool doesn't detect my hardware correctly.
http://www.nvidia.com/Download/index.aspx?lang=en-us
EDIT: 15.45 is what Nvidia lists as the latest for my NVIDIA Geforce 7025/nForce 630a (ASUS M4N68T-M V2), While ASUS offers up 15.56 in the downloads section for my motherboard.