Minimum:
* Windows XP or Vista
* 2.0 GHz P4 or equivalent CPU
* 512 MB RAM (768 MB for Vista)
* A 128 MB VRAM
* GPU w/ Shader Model 2.0 support
* 6 GB free HD space
For computers using built-in graphics chipsets:
* Intel 945GM or better GPU
* 2.6 GHz Pentium D CPU, 1.8 GHz Core 2 Duo or equivalent CPU
* 768 MB RAM
source: eu.spore.com/extra/?id=9432