Just for those of you who may stuble upon this some day... I added the following
header ("Content-Type: application/msexcel");
header("Content-Disposition: filename=filename.xls");
and it opens in open office if that is on your system and set as the default for xls files NOTE: make sure that there is NOTHING echoed outside of the <TABLE></TABLE> tags
or open office being as smart as it is will figure out what else it is supposed to be opened with! Yeah Go open office!