Recently, I wrote an article on the subject of the optimum amount of RAM for Windows Vista. And I indicated 4GB as the amount of memory that will deliver the best performances for the operating system. However, I neglected to mention that indeed, as "eiffel" pointed out, x86 versions of the operating system will allocate some address space to other resources. For 32-bit versions of Windows Vista, there is a clear distinction between the maximum supported physical memory, that is 4GB, and the actual quantity that the operating system will address, which is 2GB.

However, this got me into thinking about the minimum system requirements for running Windows Vista, and I managed to track down a Microsoft Knowledge Base article describing them. So here they are:

Windows Vista Home Basic
￭ 800-megahertz (MHz) 32-bit (x86) processor or 800-MHz 64-bit (x64) processor
￭ 512 megabytes (MB) of system memory
￭ DirectX 9-class graphics card
￭ 32 MB of graphics memory
￭ 20-gigabyte (GB) hard disk that has 15 GB of free hard disk space
￭ Internal or external DVD drive
￭ Internet access capability
￭ Audio output capability

Windows Vista Home Premium, Windows Vista Business, Windows Vista Enterprise, and Windows Vista Ultimate
￭ 1-gigahertz (GHz) 32-bit (x86) processor or 1-GHz 64-bit (x64) processor
￭ 1 GB of system memory
￭ Windows Aero-capable graphics card
￭ 128 MB of graphics memory (minimum)
￭ 40-GB hard disk that has 15 GB of free hard disk space (the 15GB of free space provides room for temporary file storage during the install or upgrade.)
￭ Internal or external DVD drive
￭ Internet access capability
￭ Audio output capability

By a Windows Aero-capable graphics card, Microsoft refers to a product with a Windows Display Driver Model (WDDM) driver, with a DirectX 9-class graphics processor unit (GPU) that supports Pixel Shader 2.0. Additionally, the graphics card also has to support 32 bits per pixel and to pass the Windows Aero acceptance test in the Windows Driver Kit (WDK).