I just received my 2.8 Quad Core Mac Pro with Nvidia 8800GT last week and I just finished installing XP with SP2. I went out and bought Call Of Duty 4 and installed it without a hitch. When I select single player an error message is displayed reading: DirectX encountered an unrecoverable error. Check the readme for possible solutions. I read through the readme and technical information but could not find a resolution. I installed the DirectX 9.0 but it still does not work. I contacted Activision and they responded... "Unfortunately we are unable to provide any support for running our PC games on Mac hardware. On the PC that error usually means that the video card is not capable of running the game or that the video drivers are out of date. Since the video cards on Mac hardware don't use standard PC Nvidia drivers we have no way of directing you to an update." Do I need to download in XP the Nvidia driver for XP or what is the problem? If someone could help I would be much obliged. Thanks for any responses in advance.