After a clean install of Windows 7 on a new hard drive on a Dell XPS 15, we struggled to get the driver installed for the "Standard VGA Adapter" as it showed in the device manager.
The Nvidia GeForce 420M driver would fail, indicating it wasn't applicable to this hardware (or something like that).
Keeping this short and to the point, it turns out that the Dell laptop requires the installation of the Intel HD Graphics Driver that is downloadable from Dell's support and drivers page for the laptop before the Nvidia video card driver. Once the Intel HD Graphics driver was installed, the Nvidia installer ran without a hitch!
Hope this helps someone who might be struggling with the same thing.
Main info found here: http://forums.anandtech.com/archive/index.php/t-2132178.html