Here's a snippet from https://alioth.debian.org/docman/vie....html#id272586
Is my Nvidia card supported?
The NVidia drivers for amd64 are known to work with linux 2.6.5 and newer kernels. The official debian nvidia-graphics-driver packages support amd64, everything works the same way as you might be used to with i386. It is not reccomended to install using the NVidia driver installer, because it is based on a different directory layout than the debian amd64 port.
Installing the NVidia drivers is documented in /usr/share/doc/nvidia-kernel-source/README.Debian
Since the documentation is i386 centristic, these are the short instructions for amd64:
* add contrib and non-free to your sources.list and update your package index files.
* Install all needed packages: gcc-3.4, nvidia-kernel-source, nvidia-kernel-common, kernel-headers-2.6.8-10-amd64-k8 or whatever matches the installed kernel.
* for sarge, or using a stock kernel up to 2.6.11: go to /usr/src/kernel-headers-2.6.8-11-amd64-k8 (or whatever headers you installed) after you unpacked the nvidia-kernel-source tarball in /usr/src and run
MAKEFLAGS="CC=gcc-3.4" make-kpkg --append-to-version -11-amd64-k8 modules_image
again, replace -11-amd64-k8 with the flavour of your kernel.
* install the created nvidia-kernel-*.deb, nvidia-glx and nvidia-glx-dev to get everything setup correctly.