Do you still have Quattro Pro? If so, you could open the files with
that, open Excel and copy/paste each sheet across, then save from Excel
(bit tedious, and some formulae between sheets may not copy correctly).
Alternatively, with the file in QP, save it as a wq1 file - then you
may be able to open it directly in Excel (you can in Excel 2k which I
use, not sure about 2003 version).
You will probably lose some formatting, and some formulae will not
convert.
Hope this helps.
Pete