Specs are here for the goliath of RTS. As promised, its requirements arent too painful to swallow. The graphics cards are a few years old and any fairly recent cpu will also be able to step up to the challenge.

MINIMUM PC SYSTEM REQUIREMENTS

OS: Windows XP/Vista/Windows 7
Processor: 2.6 GHz
Memory: 1GB RAM (XP) 1.5GB RAM (Vista/Windows 7)
Video: 256 MB VRAM DX9 compliant with Pixel Shader 3.0
DirectX Support: DirectX 9.0
Sound: No accelerated sound hardware required
Hard Drive: 4-5 GB, for full install & DirectX
Internet Connection: Cable/Broadband

RECOMMENDED PC SYSTEM CONFIGURATION

OS: Windows XP/Vista/Windows 7
Processor: 3.0 GHz Dual Core AMD or better
Memory: 2GB RAM
Video: ATI RadeonTM X1800 or equivalent card with 256 MB VRAM with Pixel Shader 3.0
DirectX Support: DirectX 9.0
Sound: No accelerated sound hardware required
Hard Drive: 4-5 GB, for full install & DirectX
Internet Connection: Cable/Broadband