The waveform graph is useful for dispaying data that occurs on regular intervals. So you can use the PlotY methods and specify the increment on the x axis. You can specify this increment in time or a double value, depending on the particular overload of the PlotY method you use.
In your case, it looks like the time intervals are not regularly spaced. It might be best to specify the XY data everytime by using the PlotXY methods. Check out the examples under C:\Program Files\National Instruments\MeasurementStudio2003\DotNET\Examples\UI\Graph to see how to use the waveformgraph and the scattergraph (also called an XY graph).
The documentation for these controls are fully integrated into visual studio .net 2003. So you can use Dynamic Help, f1 Help and all the other help features of visual studio to find out more about the methods and properties of the Measurement Studio controls.
Hope this helps
Bilal Durrani
NI