Adjustable Axis in Excel 2007

Would it be possible to program an adjustable axis in Excel? I'm
graphing multiple indicators on a 2D chart in Exel. I'm using Drop
Down boxes to select a given category(out of approximately 100
different indicators) and I would like to have a procedure that
automatically switches a given indicator to the secondary axis when
that indicator reaches a certain value, say 25,000. This sounds like
something that would be possible, but I'm just learning programming,
so I'm not sure exactly how to do it.

Thanks for any feedback in advance.