Roberto Gibbons Gomez -

You do not need to do anything special.

An XLS file from the Mac (Excel 98, X, or 2004) can be opened on Windows
(Excel 97, 2000, XP, 2003).

The XLS file format is the same (except for a few recently-introduced
features, which will be ignored on earlier versions).

- Mike

www.mikemiddleton.com