Although Windows NT 4.0 did not have native multi-monitor support in the operating system, graphics hardware vendors could incorporate some level of support through their customized graphics drivers, software utilities, or both.
Windows 2000 provided some native support for management of multiple displays to present the desktop. Windows XP took this a step further through the Windows XP Display Driver Model (XPDM) to support multiple graphics cards natively and provided the hardware vendors with the proper means to offer support in their drivers.