Variance graphs

I am trying to make two series on a line graph but want to include the difference of the two series as a bar chart. The starting point of the bar should be the series with less value such that the bar is within the two charts...I hope this makes sense. Is there a way to do this?

I have just started using EXCEL 2007 and I can't remember seeing this feature in my old version but...

under chart tools/layout/analysis there is a feature called "Up/Down Bars" which seems to be exactly what you want.

If you are using an older version try searching the help pages for these terms, you might find that the same features are available via a different route.