well, well, thats some stupid behaviour of nvidia: due to some policy the code has to be downloaded from their site each time you want to compile (at least when using this 'official' deb). The only way to avoid this is to download the correspondig nvidia-kernel-src-...tar.gz and place it in the approbiate directory (unfortunately I forgot which one, because I have nearly-lan connection and with this I don't depend on pre-fetched downloads
) Some goes for the nvidida-glx-src package. Maybe someone else is able to help here.
Bye, have fun with debian