Ok, I give up. In Excel 2007, how do I plot two data series having common
x-values? When I go to Select Data Source and Add a series, I have to
specify both x-values and y-values. If I add a second data series with the
same x-values as the first, then the x-axis labels are just 0,1,2,..., not
the x-values I specified. I do get a scatter plot with two data series, but
the x-axis is not correctly labelled.

This was no problem in prior versions of Excel, but like everything else in
the "easier to use" Office 2007, it is much harder to figure out.