Well if it is still saying nv then the driver is not installed correctly. When you follow the instructions and the display drivers are you allowing the Nvidia driver to overwrite the existing xorg.conf file as you should.
The important part of installing those drivers is the telinit 1 command. Also What architecture are you running as the 32 bit version will not install on a 64 and vice versa.
How are you connected to you display device. DVI/HDMI, VGA, CMPT etc...
If you are using the TV-outs of your Video card most of the xorg.conf file is disabled anyhow.
If you go to the Nvidia site and search for the Linux 32 or 64 bit driver then have a glance at the readme file for that driver there is a lot of info in there to help you with the install of the driver.
If you do have a corrupt driver a new installation will detect it and overwrite it with your next install.
It makes no difference if you are running a hybrid the method is the same on that machine.
On the core/hybrid - boot to a command line and login (ctl-alt-f2)
then issue a sudo su or sudo -s or what ever root command you are use to using
cd /home or cd /home/downloads or whatever directory you have setup for putting downloaded files into
dwnld the latest nvidia driver - as per the wiki - Just change the version numbers I think current is 173.14.12 but check that out at the Nvidia site to be sure.
Then issue your telinit 1 - let it run through then re login to Linuxmce and issue sudo again (change to your download directory (this may or may not be required)
Then install your driver using SH NVIDIA etc.. as per the wiki.
follow the on-screen prompts when it says the driver is installed it will end up back at a command prompt, type reboot and it should reboot and load the orbiter and then you can choose change video settings from the UI1 advanced menu and it will reboot the system and launch the a/v wizard and let you make your changes to UI2 (either mode)
Just follow the wiki to the T and you should be fine.