Excel Chart Formatting?

I assume this is the best forum for this question.

How do I set MS Excel to properly display the scale of my chart? For instance: If I have the X,Y data for a curve, let's say a circle. I use the XY scatter chart. Excel will display an ellipse. Apparently due to deltaX being different from deltaY. I'm guessing in some auto format feature.

If I drag the chart to be larger in width than height or vice versa, it will be an ellipse. How do I force the chart to set the correct width if I choose the height (or vice versa) so that the distance from 0 to 1 on the X axis is the same distance as 0 to 1 on the Y axis?

Also, if I choose to have a legend for the series, it will deform the true shape of the curve.

Even if I "Format Axis" in the Scale tab and set the min and max fields, it will deform according to the way I resize the chart with the mouse. How do I force width equal to height?

Some graphical editors will cause the width and height of a graphical object to be equal as you resize one side by pressing shift or ctrl while you drag. Any ideas? So far, I'm exporting the XY data to a CAD program to see the proper scaling, but I really think that I should be able to see the curve to scale in Excel.

Thanks.