What are the Left 4 Dead 2 system requirements

Disk DriveDVD-ROMDirect X
9.0Hard Drive SpaceAt least 7.5 GB of free spaceOperating SystemWindows 7, Vista, Vista 64, XPProcessor3.0 GHz P4, Dual Core 2.0 or AMD64X2 (or higher)RAM1 GB for XP / 2GB for VistaVideo CardNvidia 6600 or higher / ATI X800 or higher