Recently, I bumped in to some interesting fixes for problems Office 2003 users have when working with SharePoint:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;950292: if you are using Office 2003 to save documents to a SharePoint library that has multiple content types enabled, this fixes a script error when selecting the content type: ‘length’ is null or not an object. Also, in the web file properties screen, the content type you selected, is also selected in the web file properties dialog.
http://support.microsoft.com/kb/941422: if you are exporting a list to Excel, you get “cannot get the list schema column property from the sharepoint list”.
Please note that these all require SP1 to be installed.