I don't believe that you're able to do this with PivotTables. With PowerPivot yes, but you need a minimum of Excel 2010 for that.
If you can modify your data source (add columns to it) then you can do it that way in 2007 though. You just need to add a column that works out the MIN for any given date, returning 0 if the row is not the minimum. Then you could use the SUM function in the PivotTable. Does that make sense?
Bookmarks