What is the difference between a GUI and a GPU?
A GUI (Graphical User Interface) is actually the screen of the monitor and not a video card although it could also refer to a utility dialog which a user would then make selections.
A GPU (Graphic Power Unit) actually refers to onboard video out and not a video card but people get lazy and refer to a GPU as a both or either.
You can't have two different video cards on one motherboard but I expect that you have realised this by now...
I just thought I'd upddate this thread for future reference.