Grand Theft Auto IV System Requirements :

Operating System : Windows Vista SP1, Windows XP SP3, Windows 7
Processor : Intel Core 2 Duo 1.8Ghz, AMD Athlon X2 64 2.4Ghz
HDD : 16GB Free hard disk space
RAM : 1.5GB
VGA : 256MB NVidia 7900 / 256MB ATI X1900
Directx : DirectX 9 compatible

Recommended Requirements :

Processor : Intel Core 2 Quad 2.4Ghz, AMD Phenom X3 2.1Ghz
HDD : 18GB Free hard disk space
RAM : 2GB
VGA : 512MB NVIDIA 8600 / 512MB ATI 3870
Directx : DirectX 9 compatible