You are finding that the major enhancements of Microsoft's overhaul of Windows 2000 Server are the most attractive features. Those are the greatly enhanced security, the fine tuning of Active Directory and the tighter integration between Windows Server 2003 and Exchange Server 2003.
But Microsoft aimed higher than its current usage profile in Windows Server 2003, greatly expanding the scalability and sophistication of the operating system. You told us that those features aren't that compelling to you yet. Examples, the .NET-Web services technologies just aren't grabbing your attention -- maybe that's why Microsoft is de-emphasizing .NET in the generation of products that are still in development. You're also not committing to 64-bit technologies in a big way to date.
The main article below goes through the major findings of the survey. The second article takes a closer look at a company that is representative of the group of organizations jumping ahead from Windows NT 4.0 to Windows Server 2003.