Hi tonyp,
I assume based off your posts that since your are using Visual C++ 2005 you are probably using MFC which means you are using our ActiveX UI components. Now, if you were using managed C++, then you could uses our .NET assemblies but I don't think you are. Thus, you don't have to do what Jonathan is suggesting.
Instead, you can set the FormatString property either during runtime or design time for your axes. Open up the Property Pages for the graph, select the Format category, and then choose the Time style. You may want the Date style, but I will leave that up to you. See the attached snapshot, Format Option.jpg.
Once you have set that property, you need to choose your intervals in terms of what time intervals you want to display. See this post for more information as it gives some code snippets you can use. Also, its important to note how the Date/Time values are displayed and implemented. Refer to the CNiAxis main help topic and see the Note in the overview section about date/time.
Hope this helps!
Best Regards,
Jonathan N.
National Instruments