128-bit:
This refers either to the internal graphics engine or to the path from the controller to the graphics memory. 3D Prophet graphics boards have a true 128-bit subsystem because they incorporate both a 128-bit internal graphics engine as well as a 128-bit path from the controller to the graphics memory, thus providing enhanced 2D and 3D performance.

OpenGL:
A 3D image calculation standard developed by Silicon Graphics, and supported by most 3D graphic accelerator boards.

Operating system:
The program that runs the computer. This is loaded into memory when you boot up your PC and acts as an interface between hardware and software.