Well, as long as you don't use any XL2007-specific features then you
should be okay.
So, don't use more than 256 columns or 65536 rows, don't use SUMIFS or
COUNTIFS, don't use conditional formatting with more than 3
conditions, don't use xlsx/xlsm filenames, don't use full-column
references in SUMPRODUCT or array formulae ... etc.
It might be safer to develop the macros in XL2003 and then use them in
XL2007.
Hope this helps.
Pete
