Checking it only changes it for that workbook, but doesn't change the default; i.e. the next workbook opened will have it unchecked, so you would have to remember to do it every time.
I just found how to do it- open Excel 2007, browse to Office Button...Excel Options (at the bottom), Advanced, When Calculating this workbook..., then check the box for 1904 date system, press OK, then you can set any other defaults you want for the default template like the font, then do Office Button, Save As, browse to :
C:\Documents and Settings\user\Application Data\Microsoft\Excel\XLSTART
where "user" is your own user name and save it as book.xltm (Macro enabled template; not the template, not workbook).
Then when you open Excel a workbook should be created with this default template with the 1904 date system.
----- Original Message -----
Sent: Wednesday, August 13, 2008 9:17 AM
Subject: Re: OT: watch out for the two date systems of Excel
Does checking the "1904 date system" option in options/calculation help?
You learn something new every day!