Hi 
Of course! So i'm definitely on Ubuntu 12.04 then.
Errr, just occurred to me i could reattach as ods. Only the o.p. will get
the attachment, of course. I've never heard of sylk files before. The
ending was the same as other .xls files but i gather that they usually use
.slk instead.
Saving as .ods dropped file-sizes from 86-90 Kb down to under 20 Kb.
Renaming the file-ending to .zip showed both looking almost identical. The
contents.xml didn't get colour-coded by GEdit even when i switched between
different mark-up interpreters.
So, i am completely clueless as usual! Just hope the ods files help
Regards from
Tom 