In order to change your Graphics for Nascar Racing 2003 Season, you will need to enter your game, and click on: CONFIGURE 3D GRAPHICS. This will open up a Menu, where you can change your Game Graphics between: DirectX 3D, OpenGL, And one for A Dedicated Server. Try all of them out, and see which one works best for your computer.
NOTE: There will also be an option for you to run your game in a window. Running your game in a window will make your Graphics WAY better, but your not running your game in full screen.