It’s here after 6 years and more than $25 billion in R&D. According to the research firm IDC, Windows Vista will be installed on more than 90 million computers worldwide in its first year, including 35 million in this USA generating sales of about $70 billion in products and services.
According Wikipedia, Microsoft had originally hoped to have the operating system available worldwide in time for the 2006 holiday season. It was announced in March 2006 that the release date would be pushed back to January 2007, so as to give Microsoft and the 3rd party hardware/software companies additional time to prepare.
Microsoft classifies computers capable of running Windows Vista as Vista Capable and Vista Premium Ready:
A Vista Capable or equivalent PC needs to have at minimum an 800MHz processor, 512MB RAM and a DirectX 9 class graphics card. A computer that meets these requirements will be capable of running all editions of Windows Vista although some of the special features and high end graphics options may require additional or more advanced hardware.
A Vista Premium Ready PC will take advantage of Vista’s “high-end” features but will need at least a 1.0GHz processor, 1GB main memory, and an Aero-compatible graphics card with at least 128MB graphics memory and supporting the new Windows Display Driver Model. Microsoft also offers Windows Vista Upgrade Advisor from its Web site to determine the ability of a PC to run the various versions of Vista. The utility runs on Windows XP and Windows Vista.
Windows Vista & Office 2007 page at Amazon.com
Windows Vista website at Microsoft.com
In-depth article on the upgrade process at ExtremeTech