Left 4 Dead 2

System Requirements
  Minimum:

• Supported OS: Windows® 7 / Vista / Vista64 / XP
• Processor: Pentium 4 3.0GHz
• Memory: 1 GB for XP / 2GB for Vista
• Graphics: DirectX 9 compatible video card with 128 MB, Shader model 2.0. ATI X800, NVidia 6600 or better
• Hard Drive: At least 7.5 GB of free space
• Sound Card: DirectX 9.0c compatible sound card

  Recommended:

• Supported OS: Windows® 7 / Vista / Vista64 / XP
• Processor: Intel core 2 duo 2.4GHz
• Memory: 1 GB for XP / 2GB for Vista
• Graphics: DirectX 9 compatible video card with Shader model 3.0. NVidia 7600, ATI X1600 or better
• Hard Drive: At least 7.5 GB of free space
• Sound Card: DirectX 9.0c compatible sound card