Minimum:

Windows® 2000, XP with SP1 or XP64
Pentium® 4 with 1.7 GHz
512 MB RAM
DirectX® 9.0c-compatible 3D-Graphicscard with at least 32 MB RAM (ATI Radeon
8000 or GeForce 3)
DirectX® 9.0c-compatible 16 Bit-Soundcard
DVD-ROM-Drive
4.0 GB free HDD space
56K-Modem for Multiplayer