Tracy provides OneNote 2003 users with an excellent daily planner plug-in. There is also a video. Download the file and place in your notebook folder.
Because of the simplicity of the planner and wide range of templates on DIYPLanner.com, I'm including a video with a quick run through of the add-in so you can see it before you download, and also a tutorial of how to work with stationary to customize the planner for your own use. A complete installation tutorial is also included.
Source: The Student Tablet PC