I'm actually in the case described by TobiSGD.
My laptop runs a GeForce 7950 GTX that is no more supported by the upstream driver.
You have to own at least a 8 series card to have the benefits of it.
I will try the solution proposed by rkfb since it worked in his box.
AlienBOB just gave me the link of the git repository of the Slackbuilds projects.
I will pick the 302.xx branch Slackbuild and tweak it to make it compatible with my driver version.
Thanks you guys, I will let you know how this goes