Currently i USING microsoft Excel 2000, i put formula =IF(A1<>"",today(),"") in cell A2. When i key in all my entry data in cell A1, cell A2 will auto prompt up today date.But when i save the file and open it in next day all the date  in cell A2 became new date not yesterday date or previous date.How to kept  the previous date without when open the file on the day.Anyone can give advices??? Hi

Every version of Excel lacks compatibility with both later and earlier releases.
What works for one version may need adapting for the next version.

This solution works on OPENOFFICE spreadsheets, and with luck you can do SOMETHING SIMILAR with Excel 2000.

1) After creating your spreadsheet, select the cell(s) or columns which have "dynamic" dates and click COPY.
2) Choose a suitable destination and use Menu controls
Edit > Paste Special
Uncheck options "Paste All" and "Formulas"
Check options "Text" and Numbers
Experiment with other options if the first attempt is not quite right.
3) Paste to your chosen destination

That should give exactly the same appearance as the original data, but it is now static and will not get recalculated when the date or any other parameter changes.

If you wish you can select and copy a complete sheet and then select a different sheet as destination for a paste special.

You MAY be able to do a paste special direct on top of the source - but Windows get confused at the best of times and this could easily push it over the edge !!!

Regards
Alan