Another solution is to:-
cp /boot/your-vmlimuz.autoconf.h /usr/src/linux/include/linux/autoconf.h
cp /boot/your-vmlinuz.version.h /usr/src/linux/include/version.h
cp /boot/your-vmlinuz.config /usr/src/linux/.config
this should set your versions right in the src as long as you are not using anything higher than the 2.4.20 kernels.
and now the nvidas should compile correctly and install in the right place and autoload at boot.
( I think that is all that is needed, working from memory at the moment which is a bit fuzzy first thing on a sunday