Kernel source se defalutne neinstalujou...
Viz.ftp://download.nvidia.com/XFree86/Li...96/README.txt:

If no matching precompiled kernel interface is found, then the installer
will compile the kernel interface for you. However, first it will
check that you have the correct kernel headers intalled on your system.
If the installer must compile the kernel interface, then you must install
the kernel-sources package for your kernel.