Simple answer really – they do not have a name for the server side to Windows Vista yet, so they have to name it something so they just threw in the original codename for Windows Vista. With “Windows Server Codename Longhorn”, we know from the name it is a server operating system, and we also know that it’s codenamed still, which means they just haven’t thought of a name yet.

And by the way, it will not be called Windows Vista Server, or Windows Server Vista, or anything to do with Vista at all! Because it’s a business software, they tend to go along with more business style names. It’ll be most likely called Windows Server and then if it’s released the first half of 2007, it’ll be Windows Server 2007 or if it’s released in the second half of 2007, it’ll follow to the next year in name and be Windows Server 2008.