Mandrake 9.1? Pardon, I thought that the latest version of Mandrake was 9.0...
Oh, I see. The latest version of Mandrake is
9.0. You're using 9.1 beta3 or something.
Well, if Mandrake did what RedHat did and backported a bunch of threading code from the 2.5 kernel, you may not be able to install the nVidia drivers easily. But that probably doesn't matter at the moment.
The error you've posted is (most likely) a symptom of you not having kernel-source installed. Look around on the Mandrake CDs (with Mandrake 9, kernel-source was on CD 3, so a lot of people didn't download it) for a version of kernel-source that matches what uname -r
tells you. Install it and try the nVidia drivers again.
You can probably also do something like the following to make the computer give you its errors in English (so you don't have to translate yourself):
Where the "...." is you doing "make" and whatever else that gives you the error message you're seeing. No need to do this LANG stuff the first time you compile the drivers (especially if German makes more sense to you), but it might be a good idea to try before you post any other compile errors. Just an idea, feel free to ignore it.