In 2003 I set up dynamic ranges and used them as the data source in a chart
so the chart would automatically expand to included added data.

In 2007 I set up a named OpenRange on the 'Calculated data' sheet:
=OFFSET('Calculated data'!$C3,0,0,COUNTIF('Calculated data'!N:N,1))

I do not know how to reference the range in the Select Data source popup.