Microsoft is hoping that enterprises which are not looking to upgrade or replace their PCs when Windows Vista comes out will still upgrade to the core version of the operating system.

The software vendor unveiled the specifications for its Vista Capable and Vista Premium Ready programmes last week. 

The labels inform buyers that they are purchasing a system that will be able to handle the core and premium versions of the application.

The premium version features the new Aero user interface that offers advanced graphics such as semi-transparent windows and 3D application switching. The feature requires additional memory and a more advanced graphics card than the basic version.

Microsoft executives typically list the Aero user interface as one of Vista's most important features, next to the improved security. The operating system also offers enhanced search and management capabilities.

Redmond has not yet set pricing on the operating system and was unable to comment about the price difference between the two editions.

Most of today's PCs are capable of running the basic Vista, but would require a hardware upgrade to run the premium version. About half of all new systems sold today qualify for the Vista Premium logo.

Enterprises, however, may not be attracted by the advanced graphics capabilities if they require additional hardware investments.

"Vista is an important product for our entire customer set, delivering enterprise and consumer value," Windows product manager Michael Burk told vnunet.com in an interview.

"But businesses may not necessarily choose to run Aero. The basic version may be enough for them.

"The vast majority of PCs shipping today are Vista-capable. If [enterprises] are not going through a hardware refresh, they may still choose to upgrade and not get Aero."

Burk added that Windows Vista Premium is pushing the envelope more so than with previous operating systems, necessitating the more advanced hardware requirements.

Microsoft has said in the past that Vista will form the foundation of Windows versions for the next 10 years.