Wilbour Craddock, a Partner Technology Specialist at Microsoft Ireland, has done an interesting presentation discussing the virtualisation of EBS and SBS using Hyper-V. You can use Hyper-V Server 2008/2008 R2 but you could also buy the Enterprise SKU’s. Use that extra Standard Edition license as the host OS. Standard gives you 1 free license for a VM so that gives you back your license for an additional VM, e.g. SQL or Terminal Services.
Microsoft has published a document on virtualising EBS.
“Server virtualization enables multiple operating systems to run on a single physical server as virtual machines. With server virtualization, you can consolidate the workloads of multiple servers onto a smaller number of fully utilized servers. Fewer servers can reduce hardware, energy, and management costs. By using the Microsoft® Hyper-V™ technology in the Windows Server® 2008 operating system, you can run a virtualized instance of Windows® Essential Business Server on a single server or several servers.”