There are many new features which will make you more comfortable in doing your work in PowerPoint 2007 which will force you to switch from PowerPoint 2003 to PowerPoint 2007. There are number of new features in PowerPoint 2007.
File format makes your work more secure and makes a lesser size files since files become compressed.
Easy user interface to work better, efficiently and easily so that you feel more comfortable in making your presentation.
You make attractive presentation in PowerPoint 2007 because new features like Smart Art, Quick Style Gallery, Live Preview.
These are the some of reasons why you should switch to PowerPoint 2007.