You're right: the nvaudio part has nothing to do with the nvnet, and is not at all a good driver. It's in fact a kind of on the fly modification of your kernel driver, which is only valid for 2.4.18 kernels.
For the nvnet part, you did good by installing yourself the driver. And it seems afterward you ran into the same problems as me. But you should try eventually to compile yourself a kernel, like one of the pre-2.4.21 since I got the nvnet part of the nforce driver working with a 2.4.21-pre7 kernel (and not with any other one, like the 2.4.18 or 2.4.20)