Need to check these out:

from webmonkey ash
http://evoluted.net/archives/2005/06/reading_and_wri.php?d=b

from phpclasses.org
http://www.phpclasses.org/browse/package/1919.html

from sitepoint
http://www.sitepoint.com/article/pear-spreadsheet_excel_writer

from ibm
http://www-128.ibm.com/developerworks/opensource/library/os-phpexcel/
convert xml to excel:
http://www-128.ibm.com/developerworks/opensource/library/x-tipexc.html

xml and php

http://www-128.ibm.com/developerworks/xml/library/os-xmldomphp/

editing xml with php
http://www.codecomments.com/archive227-2005-5-506452.html

xml parser for php, no DTD needed!
http://minixml.psychogenic.com/