Make sure your non-free repositories are set, use Easy-Urpmi for good results. Then go to the Mandriva linux control center > Hardware > set up the graphical server, your video card should be highlighted, pick it again and you'll be asked if you want to use the proprietary driver. Tick yes and the driver will be downloaded and installed and you will have to restart the graphic server, I usually reboot. Also when your in hardware there is a box to configure the 3d effects. Your current xorg.conf is using the generic nv driver so you wont get any 3d action.
Good luck
Mike