I realise that this is a bit late for many people, but I have been helping one of my customers with a justification to move to Windows Server 2003 from Windows 2000 Server. It is specifically targeted at the main application that they develop which is a .NET Framework 1.1 based smart client app that talks, via Web Services, to a server side app also written for .NET 1.1 (this stores data in a set of SQL Server 2000 databases). I will post a series of articles extracted from this justification.
Please note: this is not an exhaustive list - it is simply the features that are of interest for this particular application.
But if you are going through a similar process at the moment it might be useful to paste this information into a document for the perusal of the powers that be.