The SideCar concept
SideCar is a portable laptop computer accessory that enables you to drive up to four extra displays from a Windows 7 / Windows XP laptop.
SideCar attaches to the laptop via a simple ExpressCard or PC Card (PCMCIA) interface, enabling easy docking and undocking of the laptop from the multi-monitor display setup. Combined with a notebook's built-in LCD display and external
monitor support, SideCar enables up to six displays to be driven by a single Windows laptop.
Each SideCar display is an independent monitor under Windows. You can run different applications on each display, move your mouse seamlessly across all displays, and even stretch applications across displays.
The following diagram shows how SideCar solutions enable a Windows notebook to drive multiple external displays. (SideCar Quad MMS example)