Topping a gratutitous bump with a less gratutitious one,
here's the minimum specs.
Operating System: Windows® XP SP3/ Windows® Vista SP2/ Windows® 7
Processor: Dual Core CPU
Memory: 2GB RAM
Hard Disk Space: 8 GB Free
DVD-ROM Drive: Required for disc-based installation
Video: 256 MB ATI HD2600 XT or better, 256 MB nVidia 7900 GS or better, or Core i3 or better integrated graphics
Sound: DirectX 9.0c-compatible sound card
DirectX®: DirectX® version 9.0c
Recommended specs are as follows:
Operating System: Windows® Vista SP2/ Windows® 7
Processor: 1.8 GHz Quad Core CPU
Memory: 4 GB RAM
Hard Disk Space: 8 GB Free
DVD-ROM Drive: Required for disc-based installation
Video: 512 MB ATI 4800 series or better, 512 MB nVidia 9800 series or better
Sound: DirectX 9.0c-compatible sound card
DirectX®: DirectX® version 11
And usual Steamworks bells and whistles (DirectX, Virtual C++ Runtime Libraries, Steam) will come on the disc.
That graphics card requirement is surprisingly high, and rules out many notebooks. Although it looks like DirectX 11 is in (although I don't know what the point of having tesselation in a Civ game is).