Microsoft Hyper V
With Hyper-V, take advantage of the cost savings of virtualisation through Windows Server 2008. Optimise your server hardware investments by consolidating multiple server roles as separate virtual machines running on a single physical machine.
Windows Server 2008 Hyper-V, the next-generation hypervisor-based server virtualisation technology, is available as an integral feature of Windows Server 2008.
Vmware Server
Accelerate server provisioning by building a virtual machine once and deploying it multiple times.
Easily evaluate software in ready-to-run virtual machines without installation and configuration.
Simplify IT testing of patches, new applications and operating systems by allowing system administrators to test in a secure virtual machine environment.
Re-host legacy operating systems such as Windows 2000, Windows NT Server 4.0 and Windows 2003 in a virtual machine running on new hardware and operating systems.