This is for Excel 2007 charts---however I'm open to other (free)
user-friendly (ie non-tech savvy) programs

I have three groups/series of data points I would like to plot on a scatter
chart. The data are growth rates from different fish groups sampled on the
same date. My problem comes in with all the points over-lap along the X-axis
(day sampled). I would like the scatter points of each group to be offset,
like in a bar graph where there are three columns. I know I can go in a
change the value for day sampled in each group to slightly off-set the
points, but just wondering if there is another way to do this without
tinkering with the data.

Example of data (but many more replicates per day)
Group Growth DaySampled
1 1.47 7
1 0.86 14
1 1.77 21
2 1.28 7
2 0.75 14
2 2,01 21
3 0.05 7
3 0.15 14
3 0.50 21