I have dell optiplex gx 520 ubuntu 12.04 my graphic card used to be an internal intel card with memory of about 256mb recently when i installed google earth it said that i dont have the required 16 mb graphic card although that message does not appear any more and google earth works fine but now i want to know is Ubuntu making full use of my computer's specs how can i make sure that my graphic card is running with all the memory??