Minimum:
        OS: Operating System: Windows XP SP3
        Processor: 2 GHz Intel Dual Core Processor
        Memory: 2GB RAM (XP), 2GB RAM (Vista)
        Graphics: NVIDIA GeForce 8500/ATI Radeon HD 2600 (256 minimum)
        DirectX®: 9.0c
        Hard Drive: 20GB free hard disk space
        Sound: DirectX 9.0c compatible
        Other Requirements: Initial installation requires one-time   internet connection for Steam authentication; software installations   required (included with the game) include Steam Client, DirectX 9,   Microsoft .NET 4 Framework, Visual C++ Redistributable 2005, Visual C++   Redistributable 2008, Visual C++ Redistributable 2010, and AMD CPU   Drivers (XP Only/AMD Only) 
 Recommended:
        OS: Operating System: Windows XP SP3/Vista/Windows 7
        Processor: : 2.3 GHz Intel Quad Core Processor
        Memory: 2GB RAM
        Graphics: NVIDIA GeForce GTX560/ATI Radeon HD 5850 (512 minimum)
        DirectX®: 9.0c
        Hard Drive: 20GB free hard disk space
        Sound: DirectX 9.0c compatible
        Other Requirements: Software installations required (included   with the game) include Steam Client, DirectX 9, Microsoft .NET 4   Framework, Visual C++ Redistributable 2005, Visual C++ Redistributable   2008, Visual C++ Redistributable 2010, and AMD CPU Drivers (XP Only/AMD   Only)