Sounds still good if runs somehow but still we would like to know what your complete build is so to suggest if any other measure will install Nvidia drivers.
Am not good at VM as I used Bactrack on VM and that drove me away from linux.
I am running an old graphics card and that do not have any supported cuda drivers so I will suggest you to install your cuda drivers only instead of installing Nvidia drivers as told in the guide. It might not install xconfig or it might but the drivers might install if you follow it correctly. If there is any step which is not clear or you get stuck please ask in the thread.