Excel export to XML

Hi

Im having problems with dates when exporting an excel spreadsheet as an XML file. I have applied an XML map to the spreadsheet in which the users enter data. They then save the spreadsheet as an xml document. Everything exports fine apart from the dates which are appearing as the XLS serial date format (a number). If I format all date fields as text then the data exports fine. The prob Im having is that the users are copying these dates from another spreadsheet where the fields are formatted as dates. When they copy into my spreadsheet it is defaulting my text field back to a date field and thus the dates are saving again as the serial date format. Is there a way tp get the XML file to save whats in the field as when I save as a CSV that date appears fine even though it is formatted as a date field.