There's a webcast next Thursday (Nov. 3) that will show ways you can leverage Office 2003's XML functionality to integrate with Web Services. It will go into both the file formats and the custom defined schema support, and should only last about a hour, so if you get a chance you should check it out: http://msevents.microsoft.com/CUI/WebCastEventDetails.aspx?EventID=1032284448&EventCategory=4&culture=en-US&CountryCode=US
Here's the description:
Learn how to use XML technologies with Microsoft Office Word 2003 and Microsoft Office Excel 2003 to build solutions. This webcast includes topics such as object models, reference schemas, and how to use custom-defined XML schema and transforms. To get the most out of this webcast, you must have a working knowledge of XML, XML technologies and Microsoft Visual Studio .NET.
Presenter: Ron Cundiff, Developer Community Champion, Microsoft Corporation
Ron Cundiff has worked in the information technology industry for nearly 10 years, most recently as a developer evangelist for Microsoft. He is a Developer Community Champion with many certifications including Microsoft Certified Solution Developer, Microsoft Certified Systems Engineer, and Microsoft Certified Database Administrator, and he is working on more. Before he joined Microsoft in 2002, Ron worked for an independent software vendor and was responsible for the design and implementation of a global online commodities exchange system.