I have an nVidia 7800 GTX card in my lappy and just downloaded an application (which includes the drivers) from the nVIdia website.

I just go to control panel, then appearance and themes, then click display and go to settings. In the advanced section the wizard was in there as an nVidia thumbnail. This allowed setting up for dual screens.

What card does your lappy/tower have? I'll sort you out if I can