A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
Tip: To draw a perfect circle hold the shift key down as you drag out the circle.
Circles have a line property, as you noticed. Select the circle and choose Format Shape. Then format the line for the circle as shown here:
http://www.dummies.com/how-to/content/how-to-format-a-line-in-office-2011-for-mac.html