Microsoft is planning to tie Windows Vista's premium graphics system, Aero, to its anti-piracy Genuine Advantage programme, according to a preliminary Vista guide posted online this week. Aero will also require pricier versions of Windows and high-end hardware, the guide said.

Microsoft said the guide is not in its final form. However, the company confirmed that Aero will require Genuine Advantage. Windows Genuine Advantage allows Microsoft to verify that customers have legitimately purchased their software.

Aero offers such features as transparent glass effects, 3D window switching and live taskbar thumbnails.

Along with a dizzying number of different levels of the Vista operating system, Microsoft is also planning to provide four different levels of user interface flashiness, with Aero at the top, according to the guide.

All versions will have a "Classic" mode, which doesn't have any particular hardware requirements, and mimics the Windows 2000 look. Lower-end hardware, and the lower-cost Starter version of Vista, will also be able to use Vista's "Basic" user interface.

At the mid-range is the "Standard" user interface, which has the same hardware specifications as Aero, namely, support for the new Windows Driver Display Model (WDDM). "Standard" can't run on Vista Starter Edition, and is aimed at Vista Home Basic users who buy more sophisticated hardware.

Aero will not be available on Starter or Home Basic; it will be available with Home Premium, Business, Enterprise, or Ultimate, according to the guide.

Besides Genuine Advantage, Aero will require a PC display adapter supporting DirectX 9 with Pixel Shader 2.0 in hardware, 32 bits per pixel and WDDM support, according to the guide.

It will require graphics memory bandwidth of at least 1,800 Mbit/s, and a minimum of 64 MByte to 256 MByte of graphics memory, depending on the monitor resolution, the guide said.

The 313-page guide to Vista features was provided to Microsoft's Technology Adoption Partner (TAP) members, and was posted on a blog operated by Microsoft presenter Fred Pullen. On Tuesday, Pullen removed the link at Microsoft's request. "Although we had permission from one of its sponsors to post the Windows Vista Product Guide to the TS2 Community Site, it isn’t quite ready for public consumption so I was asked to remove the link," Pullen wrote.

On Wednesday, Microsoft technologist Keith Combs again posted the guide on his Microsoft TechNet blog. The guide uses Microsoft's PDF-like XML Paper Specifications Document format, which requires special software to view.