From Aion's Website...
PC System Requirements
Minimum PC Requirements
* Microsoft Windows® XP SP2
* 2.8GHz CPU or equivalent
* 1GB RAM
* NVIDIA® 5900 Ultra with 128MB RAM / ATI® Radeon® x700 with 128MB RAM or higher
* 15GB hard disk space
* DVD-ROM drive
* DirectX® 9.0c (6/2008 update)
* Sound device
* Broadband Internet connection
Recommended PC Requirements
* Microsoft Windows® XP SP2/ Vista
* Dual Core CPU 2.0GHz or equivalent
* 2GB RAM
* NVIDIA® 6800 with 256MB RAM / ATI® Radeon® x800 with 256MB or higher
* 15GB hard disk space
* DVD-ROM drive
* DirectX® 9.0c (6/2008 update)
* Sound device
* Broadband Internet connection