Charles,
I know for certain that our NI-DAQ software and LabVIEW are not officially supported under Windows Server 2003. Our NI-488.2 driver is also not supported but I have not personally tested it and there is no documentation stating that it will not work, just that it isn't supported.
The current supported operating systems that will work for sure with the PXI-GPIB are Windows 95, NT, 98, 2000, and XP. The latest version of NI-488.2 is 2.3. Please let me know if you need any more information.
Craig H.