When this installer 'creates' a new driver for you it installs it in the necessary location. You must then edit the config file for the XFree86 server to make it USE the new driver. The directions for editing this file are given in the readme available to download on nvidia's driver download page.
Edit the XF86Config-4 file in the directory /etc. Under Device, change 'nv' to 'nvidia'. other changes are also in the readme, read it
IF the installer does NOT end saying it successfully completed installer the driver, then you need to find out why, pay attention to what it tells you.