To learn more about PowerPoint views, see When and how to use views in PowerPoint 2007.
By default, PowerPoint opens in Normal view, displaying the thumbnails, notes and slide view. If you prefer, however, you can specify that PowerPoint open in a different view, such as Slide Sorter view, Slide Show view, Notes Page view, and variations on Normal view.
Click the Microsoft Office Button , and then click PowerPoint Options.
In the PowerPoint Options dialog box, click Advanced on the left pane.
Under Display, in the Open all documents using this view list, select the view that you want to set as the new default, and then click OK.