In this section of the MSDN Library, you'll find technical articles that show how to reuse legacy forms and documents using the new XML mapping feature, how to use smart tags to enable data drill-down, and how to import XML maps, XML lists, and dynamic chart sources in Microsoft Office Excel 2003—and even a super-easy guide to the Excel object model.
You can use the TOC to your left to navigate through the Library articles.
For code samples, downloads, add-ins, schemas, and more information about Excel, please visit the MSDN Office Developer Center.