I know this doesn't answer your question, but it's some additional info.
The 4191 driver readme says:
"The NVIDIA Accelerated Linux Driver Set supports all standard VGA and VESA modes, as well as most user-written custom mode lines; double-scan modes are supported on all hardware, and interlaced modes are supported on:
GeForce2 GTS/GeForce2 Pro
and all TNT products."
By the way, I've made a couple of posts asking about broken interlace mode support in the drivers, so if you get a card that has working interlace hardware support and you do a good modeline you can expect to get messed up video output.
To my knowledge, interlace is not working in any of the 4xxx drivers, and I have no idea about earlier. I would try 3xxx drivers but I've got issues with the version of gcc used to compile the non-open source nvidia-compiled object code.