roots@harima:~$ gcc -v
Reading specs from /usr/lib/gcc/i486-linux/3.4.4/specs
Configured with: ../src/configure -v --enable-languages=c,c++,java,f77,pascal,objc,ada,treelang --prefix=/usr --libexecdir=/usr/lib --with-gxx-include-dir=/usr/include/c++/3.4 --enable-shared --with-system-zlib --enable-nls --without-included-gettext --program-suffix=-3.4 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt --enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm --enable-java-awt=gtk --disable-werror i486-linux
Thread model: posix
gcc version 3.4.4 20041218 (prerelease) (Debian 3.4.3-6)
I already have kernel-kbuild and nvidia-kernel-sources installed. I've compiled my own kernel on this machine, but it always turns out to be an i686 kernel even if I select AMD64 as my processor in make confing, because (like you said) I need to cross-compile my kernel. I've tried cross-compiling my kernel several times and it always ends in failure (I think it's because I don't have gcc and some libraries setup correctly for a 64-bit compile). That's why I am trying to use the stock kernel from the Debian archives as the kernel to install the nvidia drivers onto, but it seems from what you said that I have
to use cross-compiling on the nvidia drivers in order to do this.
Unfortunately I'm really busy lately and don't have the time to mess around hacking kernels and such (since I already wasted my past two weekends doing that). So I'll either have to wait until I find an easy step-by-step guide so I don't have to deal with this all, or I'll have to wait until my life gets less hectic.
This is the closests I've found to a good cross-compile guide: http://www.larryowen.org/amd64/kernel.html