Hyper-V Server 2008 is not the same thing as Windows Server 2008 running Hyper-V. It’s important that you understand the distinction between these two when selecting the best solution for your deployments.
Hyper-V can be deployed in two basic ways: as an add-on to Windows Server 2008 or as a stand-alone product. Hyper-V Server 2008 is a stand-alone product that only provides virtualization. There is not support for extra services such as DHCP, DNS or Internet Information Servers. Now, don’t misunderstand me; you can install virtual machines that provide all of these services, but the services do not run "on the Windows Server" in the same way that you may be used to. Of course, and most don’t realize this, even with Hyper-V running on Windows Server 2008, your extra services are running in a virtual machine, Microsoft just likes to call it the "parent partition".
Hyper-V Server 2008 is completely, totally and without exception free; however, you still have to pay for the licenses to run the needed OS within each virtual machine. If you want to play with Hyper-V as a Linux server virtual host, you can built everything without a single license fee. Hyper-V "running on" Windows Server 2008 requires that you first purchase Windows Server 2008 licenses. Here’s a great tool that Microsoft has released to help you calculate the cost of implementing Windows Server 2008 running Hyper-V (NOTE: This tool does not provide support for cost calculations related to Hyper-V Server 2008): http://www.microsoft.com/windowsserver2003/howtobuy/licensing/calculator.mspx
In summary, just one more time, two basic products exist: Hyper-V Server 2008 (free) and Windows Server 2008 "running Hyper-V" (not free no matter how you slice it because you have to buy Windows Server). And there you have it.
