I strongly suggest purging your Kubuntu installation and starting from scratch - since it's not now clear how much you've messed everything up.
You don't need NVIDIA installer to configure your xorg.conf file, nowadays you only need a small file in /etc/X11/xorg.conf.d directory, i.e. you can grab one from here: NVIDIA configuration file for X.org server >=1.8
I think you should use Ubuntu supplied binary NVIDIA drivers (that will save the pain of upgrading kernels because I bet your father won't be willing to study how to recompile NVIDIA kernel interface) or nouveau if you don't intend intensive gaming. Nouveau is still kinda rough on edges, so NVIDIA binary driver is still the best choice for NVIDIA GPUs.