Power Publishing Gimp, Inkscape, Scribus

Clicl on "Layer" in the menus and add a layer. Rename it shape. We'll use this as a path for the text.

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Next select the shape layer in the layers list on the bottom of the window. Use the circle tool and create a circle that almost fills the image. Use the <ctl> key while changing the size to keep it a perfect circle. "Right click" and select "Fill and stroke" to ge the fill dialog box.
Click on the small "x" to make the circle transparent. Then use the stroke paint and style menus to get a thin black line around the edge of the circle.
You'll need to resize the circle so that it leaves space on the outside for the lettering we'll add. We'll be hiding the circle later so don't worry about it showing up in the final image.

Use the "A" text tool and enter some text for your logo. Use the "T" text tool in the top menu to change color, size and font.

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Now click on the text with the arrow tool and shift-click on the circle edge. Both should be selected. From the "Text" menu on the top menu bar, select "Put on path." The text is now attached to the circle. Move or rotate the circle (click once or once again to switch) and the text moves too. Rotate the circle so that the text is even. You can turn on the grid from "View >> Grid" or use a guide (blue line, just click on the ruler above the image and drag down a guide) to be sure the words are even. Rotate the circle to adjust if needed.