Microsoft has pushed back the release of the first public beta for Windows Server virtualization, code-named Viridian, from the first half of 2007 until the second half of the year so that it can meet its internal goals for performance and scalability Viridian is Microsoft's Windows hypervisor technology that will run beneath the operating system and manage resources for multiple virtual machines. But Microsoft is way behind its Linux competitors on this front, as Red Hat and Novell's SUSE have both already integrated the Xen hypervisor technology into their server products. The release of Virtual Server 2005 R2 service pack 1 has also been pushed back a quarter and will now ship by the end of June 2007, but Microsoft customers and partners will be able to download and use a Release Candidate version of the product by the end of April. The second beta for Virtual Server 2005 R2 SP1 can be downloaded here.