I am using Excel 2003 and cannot figure out how to plot means and standard
error bars, where I have data arranged like this:

3 5
5 9
6 4
7 3
Mean Mean

Hi Rik,
Make two series for your chart,

Series 1 is data i.e.
x y
3 5
5 9
6 4
7 3

Series 2 is means i.e.
x y
Mean Mean

Series 2 will give you a single point on your chart, right click that
point and select Format data series, click on the x error bars tab
select "both" then click percentage and set it to 100% and OK out.
You will have line stretching the full width of your chart.

HTH
Martin