In order for you to play Call of Juarez on Windows with minimal graphics settings, your computer must meet the following requirements
Windows® 2000/XP (only), 2.2 GHz Pentium® 4, AMD Athlon™ 2400+, or 2.4 GHz Celeron or better (3 GHz Pentium 4, AMD Athlon 3000+, or 3 GHz Celeron or better recommended), 512 MB RAM (1 GB recommended), nVidia: GF6600, ATI: Radeon 9800 or better video card*, DirectX 9-compliant sound device, DirectX 9.0c or higher, 2 GB Hard Drive Space, Windows-compliant mouse and keyboard
*Supported Video Cards at Time of Release:
nVidia GeForce 6600, 6800, 7600, 7800, 7900 ATI Radeon: 9800, X800, X1300, X1600, X1800. X1900