When you get a GPIB controller from NI, you get support for C, C++, VB, LabVIEW, .NET, etc.
That tutorial is very old and spcifically deals with communicating to the very old, dedicated GPIB controllers like the ones HP used to make. Is this what you want to do or is it something else. If it's just GPIB example programs you are looking for, they are included with the driver software.