Here's an update of my current situation.
Linux version 2.4.18
GeForce 3 Ti 500
The first error I received was the compiler mismatch error. I remedied this by re-compiling the kernel. This was my first time so I'm not sure if I did it correctly, but I didn't receive any errors. The next error was:
In file included from nv.c:14:
nv-linux.h:24: linux/modversions.h: No such file or directory
make: *** [nv.o] Error 1
Someone told me on a forum that I needed the kernel header files. I installed the kernel-headers-2.4.18 package, but I wasn't sure where to go from there, so I copied the directory /usr/src/kernel-headers-2.4.18/include/linux to the nvidia directory. I did this because it contained the modversions.h file, along with other headers. When I entered make install, it compiled for a little while, then gave the error:
depmod: *** Unresolved symbols in /lib/modules/2.4.18/kernel/drivers/video/NVdriver
make: *** [package-install] Error 1
So I don't have a clue what to do anymore. I don't want to crawl back to Red Hat. Debian is a very efficient system, and I just want my graphics to work correctly.