Depth buffer bits

I''m writing some OpenGL code for laptops so I''m trying to cut down memory size and load, etc. I''m thinking for cutting down DepthBuffer size from 32-bit to 16-bit. My Frustrum set by GluPerspective have a zNear and zFar of 0 to 10000. Is it safe to say that 16bit depth buffer is sufficient in my case, because 2^16 > 10000? Is my reasoning correct? This is set with PixelFormatDescriptor, right? (What other flags can I set to optimize?) PIXELFORMATDESCRIPTOR pfd = { sizeof(PIXELFORMATDESCRIPTOR), // Size of this structure 1, // Version of this structure PFD_DRAW_TO_WINDOW / // Draw to Window (not to bitmap) PFD_SUPPORT_OPENGL / // Support OpenGL calls in window PFD_DOUBLEBUFFER, // Double buffered mode PFD_TYPE_RGBA, // RGBA Color mode 32, // Want 16bit color 0,0,0,0,0,0, // Not used to select mode 0,0, // Not used to select mode 0,0,0,0,0, // Not used to select mode 16, // Size of depth buffer 0, // Not used to select mode 0, // Not used to select mode PFD_MAIN_PLANE, // Draw in main plane 0, // Not used to select mode 0,0,0 }; // Not used to select mode