Say you have a big collection of excel 97-2003 format files (.xls) and a lot
of them have links between each other. Your department plans to make the
move from Excel 2003 to Excel 2007. New files that you create are saved as
2007 format (.xlsx) and they want to link to the 97-2003 (.xls) files. Is
there a necessity to convert all the old 97-2003 (.xls) files to 2007 (.xlsx)
or is it OK to just leave them as is and assume the links will be OK between
the 2 versions?