Take a sneak peek at your Slide Master's layout before you apply it (PowerPoint 2007)

PowerPoint 2007’s menu setup incorporates a View tab that groups several items into a block called the Presentation Views. This is where you'll find the new Slide Master view (formerly at View | Master | Slide Master), along with Notes Master, Handout Master, Zoom, Color options and so on. Each Slide Master comes with a set of layouts visible as thumbnails along the left side of the main slide window. Each thumbnail incorporates your slide's theme, graphics, fonts, and so on, so you can see how the slide will appear before you ever apply the layout.