I assume that you are using Mandrake 10.0 (and therefore urpmi with relevant sources set - if those sources are not properly set, I advise you to google for " "easy urpmi"
- to identify which kernel you currently use, type
"cat /var/log/dmesg" in a console
the kernel version is the first line
it should be something like 2.6.3-4mdk or 2.6.3-7mdk or 2.6.3-8mdk depending on whether you did upgrade your kernel
- to identify your installed kernel sources, type
"cd /usr/src" <== kernel sources are installed in this directory
You should get something like that
lrwxrwxrwx linux -> linux-2.6.3-8mdk/
Note that you may have several kernel sources installed. The one used by default when compiling modules is the one referenced by the symbolic link "linux".
If your kernel source doesn't match your kernel, then check what is available to install :
"urpmq -f kernel-source"
and install the one you want "urpmi kernel-source.blablabla"
==> you may also do this through the rpmdrake gui.
Once kernel and kernel source match, running the nvidia installer is a snap.
I hope it helps,