AMD: http://microsoft.amd.com/us-en/Home-Page/Are-You-Ready-/System-Requirements.aspx

System Requirements

Minimum requirements for Windows Vista™ Capable PCs:

    * Modern PC processor, at least 800 MHz
    * 512 MB of system memory
    * Graphics card that supports DirectX 9


Minimum requirements for Windows Vista Premium Ready PCs:

    * 1 GHz 32-bit (x86) or 64-bit (x64) processor
    * 1 GB of system memory
    * Graphics card that supports DirectX 9, with a WDDM driver, 128 MB of graphics memory (minimum), Pixel Shader 2.0, and 32 bits per pixel
    * 40 GB hard drive with at least 15 GB of free space
    * DVD-ROM drive
    * Audio output capability
    * Internet access capability