Microsoft Hyper-V Server 2008 described as a standalone version of the Hyper-V role that's now included in Windows Server 2008, Hyper-V is sort of a bare-metal version of Microsoft's hypervisor. It installs much like any version of Windows Server 2008, but when all is said and done you're left with a command line UI so start that it makes Server Core look like a rich interactive video game by comparison. This might just be a first for a Microsoft server product: As configured out of the box, you actually can't do anything with Hyper-V.
Missing from this list, of course, are such niceties as "install a guest OS on top of the hypervisor." To perform such an action, you'll need to hit the server remotely. That can be done with Hyper-V Manager, a sort of bare-bones management tool that comes with the Hyper-V role on Windows 2008, or can be installed separately on Windows Vista with SP1. How you make this connection, however, will determine your level of success.