Operating System Like many PC games, COD4 is meant to be played on the PC, requiring either Windows XP or Vista as its underlying operating system. Central Processing Unit COD4 should be run with a 1.8 GHz dual-core CPU or higher. Random Access Memory COD4 requires at least 512 MB of RAM to operate on the Windows XP platform, and 768 MB of RAM if you run it on Vista. Hard Drive You must have at least 8 GB of free space on your hard drive to install and operate COD4. Video Card COD4's graphics engine requires, at minimum, the NVIDIA Geforce 6600 or the ATI Radeon 9800Pro.