The official requirements, both minimum and recommended, for Civilization IV: Colonization were published yesterday at 2K's Colonization forum by 2K_Elizabeth. As expected, they are not too different from Civ4: Beyond the Sword's requirements, though the video cards need to now contain Shader 1.1 support. You can see the full details below:
Thanks to Modeltrainman for noticing this information!
MINIMUM SYSTEM REQUIREMENTS
Operating System: Windows(r) 2000/XP/Vista
Processor: 1.2 GHz Intel Pentium 4 or AMD Athlon processor or equivalent
Memory: 512 MB RAM
Hard Disk Space: 900 Megs Free
CD-ROM Drive: 4X Speed
Video: DirectX 9.0c-compatible 64 MB video card with Shader 1.1 Support
or better
Sound: DirectX 9.0c-compatible sound card
DirectX(r): Sid Meier's Civilization IV: Colonization DirectX(r) version
(included on game disc)
RECOMMENDED SYSTEM REQUIREMENTS
Operating System: Windows(r) 2000/XP/Vista
Processor: 1.8 GHz Intel Pentium 4 or AMD Athlon processor or equivalent
Memory: 1 GB RAM
Hard Disk Space: 900 Megs Free
CD-ROM Drive: 4X Speed
Video: 128 MB Video Card w/ DirectX 9 support (pixel & vertex shaders)
Sound: DirectX 9.0c-compatible sound card
Thanks to Modeltrainman for noticing this information!