System Requirements:
OS:Windows XP/Vista/Vista64/Win7,
Processor:Intel Core 2 Duo 2.4 GHz,
Memory:1GB of RAM (2 GB for Vista),
video card with Shader model 3.0 - NVidia 7600, ATI X1600 or better
at least 7.5 GB of free hard disk space,
DirectX 9.0c - compatible sound card

Download Links:
Download Left 4 Dead 2 Cold Stream