Note - Click here to Add Clip Art and Pictures in PowerPoint 2007
Use A Content Slide Layout
PowerPoint offers you a number of different ways to add clip art and pictures to a presentation. Perhaps the easiest way to do so is to select a Slide Layout that contains a placeholder for content such as clip art and pictures. Select Format > Slide Layout from the menu to bring up the Slide Layout task pane.
There are a number of different Content Layout slides available for you to choose from. To add a single picture or a piece of clip art, click on a simple layout such as Content or Content and Title from the task pane and the layout of your current slide will change to match your choice.