Excel 2007 Saving Cell types in XLS format

[Justin]

I am in a spreadsheet and I set an entire column as a date type (right
click the top, format cells and I choose one of the date formats).
I save it as an xls - Excel 2003 file and when I go back in, that column
is set at a currency.
I have to save it as an xls and not an xlsX file because I am working
with people using other office suites - including *gasp* non Microsoft
programs.
How can I keep those cells from changing?
I have seen this happen on Excel 2008 on the Mac as well as 2007 on Windows.

 

[Justin]

I am in a spreadsheet and I set an entire column as a date type (right
click the top, format cells and I choose one of the date formats).
I save it as an xls - Excel 2003 file and when I go back in, that column
is set at a currency.
I have to save it as an xls and not an xlsX file because I am working
with people using other office suites - including *gasp* non Microsoft
programs.
How can I keep those cells from changing?
I have seen this happen on Excel 2008 on the Mac as well as 2007 on
Windows.

Nice.
Thanks for the help.