In a move aimed at allowing more computers to run different software systems simultaneously alongside Windows, Microsoft said Tuesday it is making the specification for its virtualization format software freely available to all software developers and customers.The software, called Virtual Hard Drive (VHD), allows a single hardware device to have multiple operating systems and applications running simultaneously.The initiative is an extension of what Microsoft calls its Open Specification Promise launched last month, when it made specifications for 35 of its Web services freely available. More than\u00a060 companies have licensed VHD from Microsoft in recent years. By making the software freely available, Microsoft expects 500,000 virtualized servers will be sold this year. According to forecasts by researcher IDC, the number should rise to 1.2 billion by 2009.\u201cWe are focused on delivering interoperability by design,\u201d said Bob Muglia, senior vice president of the Server and Tools Business at Microsoft. \u201cThis means that customers have control over their data while vendors provide technologies that connect diverse systems. By having the VHD specification available under the OSP, the technology is viable for any development or business model.\u201d\u201cRed Hat welcomes the extension of the Open Specification Promise to additional specifications, such as the VHD Image Format Specification,\u201d said Mark Webbink, deputy general counsel for open-source software distributor Red Hat. But he cautioned that \u201cwhile a positive step, there are still significant barriers to full interoperability with Microsoft technologies that still need to be addressed, particularly with respect to interoperability with technologies developed and licensed as open source.\u201d\u201cRed Hat would welcome the same sort of dialogue and responsiveness that Microsoft displayed in the development and application of the Open Specification Promise in the context of the Work Group Server Protocol Program, proposed as a remedy in the E.U. competition proceedings, in order to truly provide software choice," Webbink added.The launch of the Open Specification Promise (OSP) last month was seen by some as a positive development in its relations with the open-source software community.\u201cI see Microsoft\u2019s introduction of the OSP as a good step by Microsoft to further enable collaboration between software vendors and the open-source community,\u201d said Lawrence Rosen, a lawyer with technology law firm Rosenlaw & Einschlag, and a lecturer in law at Stanford University.-Paul Meller, IDG News Service (Brussels Bureau)Related Links:\n\nMicrosoft Releases Vista Code to Security Firms\n\nMicrosoft Allows 1 Vista Transfer Under New License\n\nMicrosoft: Vista-Ready Products to Ship by Holidays\n\nMicrosoft Windows RC2 ReleasedThis article is posted on our Microsoft Informer page.\u00a0For more news on the Redmond, Wash.-based powerhouse, keep checking in.Check out our CIO News Alerts and Tech Informer pages for more updated news coverage.