VMware has unveiled an entry-level virtualisation product called VMware Server for Linux and Windows, which it is making available free of charge. 

The company still plans to sell its enterprise-class products such as ESX Server and VirtualCenter for a fee, and will get additional revenues from the sale of management tools.

Virtualisation software has become a mainstream technology in recent years. It allows users to partition one physical server into several virtual units, each of which behaves like a standalone server with a discrete operating system.

The technology allows for server consolidation and lets organisations quickly set up servers for new applications.

VMware is currently the largest player in the virtualisation market, but is under threat from Microsoft's Virtual Server 2005 and the open source Xen project, which is supported by Intel and the University of Cambridge. 

Gordon Haff, a senior analyst at Illuminata, suggested that the introduction of the free suite was a "brilliant move" in the circumstances.

"With Xen still in pre-production and Microsoft's Virtual Server 2005 just getting going, there is a window for VMware to insert itself as the best premium x86 virtualisation product, and the best free/cheap one as well," Haff wrote on his company's blog. 

"VMware [has] just made life very difficult for Microsoft and likely even reduced the rate at which Xen will be deployed on Linux servers."

A beta of the VMware Server is available for download here.