Where are the kernel headers?

In attempting yet again to install the latest NVIDIA drivers, I've run into a problem with unresolved symbols. According to the writeup, the kernel module has most likely been built using header files for a different kernel version than the one I'm using (stock 2.4.4). To fix that I need to provide the path to the kernel headers. But where are they? If I knew at least the name of the directory containing them or some of the files in that directory I could probably find the path by using "locate'. Paul