When you save your document with the option "Save as", you will find a
listbox where you'll find the option 'Microsoft Excel 97-2000 & ...".
Ofcourse when you save the document in this version you have to Recheck
everything because it's possible that some of the things you
programmed/implemented do not work, work half or just don't exist
anymore in that version... then you'll have to re-invent (the wheel ?
;-) )

Bye
Baj