Which page did you get NVchooser.sh from? Grab it from the same page as what has the driver version you want...
So do it like this:
1) Decide which driver version to get (if you go to nvidia.com, hit drivers, and fill in graphics driver, geforce, and linux ia32, you'll go to the most current version's page -- but some people have been having problems with 4191, which is probably why volt suggested 3123)
2) Go to that version driver's download page
3) Grab the NVchooser that's linked there
4) Run it
5) Download that file from the same page