Recommended:

OS: Mac OS X 10.5.8, 10.6.1
Processor: Intel Core 2 Duo CPU
CPU Speed: 2.4 GHz
Memory: 2 GB RAM
Hard Disk Space: 1 GB free disk space
Video Card: (ATI): Radeon X1600 Video Card (NVidia): GeForce FX 8600
Video Memory: (VRam): 512 MB
Multiplayer: Internet (TCP/IP) and LAN (TCP/IP) play supported. Internet play requires broadband connection.
Media Required: DVD-ROM Drive
Peripherals: Macintosh mouse and keyboard
Supported Chipsets: ATI RADEON X1600, X1900, 2400, 2600, 3870 NVIDIA GEFORCE 7300, 7600, 8600, 8800, 9400, 9600, GT 120
NOTICE: Apple original CPU’s only, CPU upgrades not supported.
NOTICE: Intel integrated video chipsets are not supported.
NOTICE: This game is not supported on volumes formatted as Mac OS Extended (Case Sensitive)

Sid Meier's Civilization IV: Colonization screenshots