There are two versions of BioShock; the PC and Xbox 360 version.

Minimum Requirements

CPU – Pentium 4 – 2.4GHz Single Core processor +
RAM – 1GB
Video Card – Direct X 9.0c compliant video card with 128 MB RAM (NVIDIA 6600 or better/ATI X1300 or better, excluding ATI X1550).
Sound Card – 100% DirectX 9c compatible sound card
Hard disk space – 8GB free space

Recommended Requirements
CPU – Intel Core 2 Duo processor
RAM – 2GB
Video card – DX9 – Direct X 9.0c compliant video card with 512MB RAM (NVIDIA GeForce 7900 GT +) / DirectX10 – NVIDIA GeForce 8600+
Sound Card – Sound Blaster X-Fi series ( Optimized for use with Creative Labs EAX ADVANCED HD 4.0 or EAX ADVANCED HD 5.0 compatible sound cards)

Operating System:
Windows XP (with Service Pack 2) / Windows Vista.