Related - Align Graphic Objects in PowerPoint (earlier versions)
Select the Graphic ObjectsGraphic objects can be lined up horizontally or vertically -- to the left, right, top or bottom -- in relation to each other or relative to the slide. It is a matter of a few simple steps in PowerPoint 2007
Start by placing your mouse near the outer edge of one of the graphics and drag a window to surround all objects to be included in the alignment.