Excel 2007 added some new formulas (IFERROR, SUMIFS, and others) so
these will not be compatible with 2003. Also, functions that in 2003
and earlier were part of the Analyis Tool Pack were made native
functions in 2007, so in 2003 you'll have to load the ATP.
Cordially,
Chip Pearson
Microsoft Most Valuable Professional
Excel Product Group
Pearson Software Consulting, LLC
www.cpearson.com
(email on web site)