How do I install two video adapters drivers using the same WDDM driver?

Microsoft said: "The user could change the graphics hardware configuration
by choosing multiple graphics adapters that use the same WDDM driver.
Graphics adapters from the same ASIC family generally have the same graphics
driver.
In late 2006, each of the major graphics vendors had a single WDDM driver
for all supported WDDM graphics adapters."

http://www.microsoft.com/whdc/device...imonVista.mspx

http://www.realtime-vista.com/instal..._dual_moni.htm

We we trying to upgrade all the Vista systems with Nvidia GeForce FX5500
adapters in our office to dual displays. So, how do we do it?