Ok, sorry didnt work out for u first time, I see why now, your kernel sources are not bf like the debian kernel your currently booted up to
ln -s kernel-source-2.4.18 linux
notice at top, should be like this:
VERSION = 2
PATCHLEVEL = 4
SUBLEVEL = 18
EXTRAVERSION = -bf2.4
save Makefile and exit vi.
make install SYSINCLUDE=/usr/src/linux/include
from the NVIDIA_kernel... dir.