More idea ? Yes but it's weird :
./NVIDIA-Linux-x86-1.0-5336-pkg1.run -k=2.6.6 --kernel-source-path=/usr/src/linux/include/linux

./NVIDIA-Linux-x86-1.0-5336-pkg1.run -k=2.6.6 --kernel-source-path=/usr/src/linux/include

And at last look in the file :
/lib/modules/2.6.6/build/include/linux/version.h

What is the value for UTS_RELEASE ?

And also this value should be the same in
/usr/src/linux/include/linux/version.h

??
there is no version.h

greets

You replied before I edit the previous post Then what is the value for UTS_RELEASE in
/usr/src/linux/include/linux/version.h ?

im sry, but there isnt version.h, too

greets

Ok I think your best way is :
download a 2.6.6 kernel from www.kernel.org
untar the file in /usr/src so you obtain a linux-2.6.6 directory in /usr/src
delete the file named 'linux' in /usr/src (a link to a directory)
ln -s linux-2.6.6 linux
./NVIDIA-Linux-x86-1.0-5336-pkg1.run -k=2.6.6 --kernel-source-path=/usr/src/linux

If that fails I can't help

[ edit ]
if you want compile your own kernel copy the config file for the actual kernel in /boot (named config.2.6.6 or so) and name it .config in /usr/src/linux-2.6.6 directory so you will just start from a workable config, just set a few features like processor (features which you are sure) then make and make modules_install, easy

Yeah i suggest compiling the kernel yourself.. But first try to do this.. Cd to the directory you have the file in like this

cd /path/to/directory

Then when your in that directory do

sh NVIDIA-Linux-x86-1.0-5336-pkg1.run

If that doesnt work then compile your own kernel..

I think your missing the 2.6.6 kernel headers. Atm you should have the kernel-headers-2.4.22-i386-1.tgz package installed, but they won't work with 2.6. I don't think you'll need to compile the kernel. Just remove the 2.4 package and copy:

The folders:
/usr/src/linux-2.6.6/include/asm-generic
/usr/src/linux-2.6.6/include/asm-i386
/usr/src/linux-2.6.6/include/linux

And the symlink
/usr/src/linux-2.6.6/include/asm -> /usr/include/asm-i386

Over to /usr/src/include.

So you'll be able to compile programs against the 2.6 kernel, but not against the 2.4 kernel anymore.

cd /usr/src/linux-2.6.6
make mrproper
make menuconfig (console) or make xconfig (X, you need tcl\tk installed)
load altenative config file (/boot/config-2.6.6) from running kernel
and fix what you need
at last read the manual how to compile 2.6.6 kernel and compile ;]