My answer seems to have disappeared. I summarize here.
"modinfo nvidia-curred" works well. CUDA libraries are installed.
For nvidia-cuda-toolkit, nvidia offers SDK packages for Ubuntu, not for Debian. I don't like to get into troubles with Ubuntu, which, unlike LinuxMINT, is not compatible with Debian.
I tried GNU "CUDA-Z-07.189.run" (don't remember from where it was downloaded). However it does not find the shared libXrender.so.1, even if made available into the same folder of CUDA-Z.
Actually
root@gig64:/home/francesco# apt-file search libXrender.so.1
libxrender1: /usr/lib/x86_64-linux-gnu/libXrender.so.1
libxrender1: /usr/lib/x86_64-linux-gnu/libXrender.so.1.3.0
libxrender1-dbg: /usr/lib/debug/usr/lib/x86_64-linux-gnu/libXrender.so.1.3.0
root@gig64:/home/francesco#
francesco@gig64:~$ echo $PATH
/opt/namd2.9_cuda4.0_2012-09-26/bin:/opt/namd2.9_cuda4.0_2012-09-26/bin:/opt/namd2.9_cuda4.0_2012-09-26/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/opt/amber12/bin:/opt/amber10/bin:/opt/UCSF/Chimera64-2012-10-10/bin:/opt/namd2.9_cuda4.0_2012-09-26/bin/namd2:/opt/amber12/bin:/opt/amber10/bin:/opt/UCSF/Chimera64-2012-10-10/bin:/opt/namd2.9_cuda4.0_2012-09-26/bin/namd2:/opt/amber12/bin:/opt/amber10/bin:/opt/UCSF/Chimera64-2012-10-10/bin:/opt/namd2.9_cuda4.0_2012-09-26/bin/namd2
francesco@gig64:~$
Should /usr/lib/x86_64-linux-gnu be put on my path explicitly?
Thanks
francesco pietra