I was looking in the NVIDIA folder and it looks like I did install nforce drivers. I have the 15.35 and the 15.51 downloaded. What's interesting is that I'm using the older driver from the 15.35 package for my network, so I'm wondering if maybe I had the same issue as you did and don't remember.
Try downloading this slightly older driver, uninstalling all of your nforce drivers, and install this one.
Here is what my networking properties look like.
I've been doing some searching though and I'm wondering if NVIDIA put those options in for your nic or not. It is supposed to support Jumbo frames but from what I've been reading the XP drivers never got the option for it.
Can you see what your Device ID is?
It should be the PCI\VEN_10DE\DEV_****
The last 4 numbers will let me see what options should be installed according to the inf file.