Compatibility Pack for 2003

This allows files created in 2007 and 2010 to be opened in 2003
This pack is for Excel, Word and PowerPoint
Once the pack has been installed you will be able to open, edit, save and create files using the new XML file formats.
The pack can be downloaded Free from the microsoft website
You may see a small "file conversion in progress" dialog box.

The following files you cannot open with the compatibility pack:
Word - dotx

When saving a file to the Excel 97-2003 file format, Excel will scan the file and display the following dialog box to help you make a decision about potential compatibility issues.
The compatibility checker can be run manually if you want to from (Office > Prepare > Run Compatibility Checker).
SS

Check compatibility when saving this workbook - The compatibility checker works on a workbook by workbook basis. Un ticking this option will stop the compatibility checker from running the next time you save this workbook. Without the prompt any new features will be lost when saving this file in an earlier file format.
Copy to New Sheet - The workbook will not be saved and a new worksheet will be inserted displaying a compatibility report.
Continue - The workbook will be saved.
Cancel - This dialog box will be dismissed and the Save As dialog box will be displayed.

Office 2007 application can still open files using the older format.
You can save a file you created in Office 2007 as a 97-2003 file format although some features that are new to Office 2007 will be lost in the conversion.

A list of issues will be reported to you and you can decide whether to accept these losses or make modifications before saving the spreadsheet.

If you regularly share files with people who use older versions of Office you have two options:
1) Save your files in the older format
2) Convince your colleagues to install a conversion utility that allows them to open (but not save) files created in the new format.

How can I convert a spreadsheet from the old file format to the new Excel 2007 format ?

Open the workbook as normal which will open it in compatibility mode.
Select (Office > Convert).
This will convert your workbook to the new file format and allow you to use all the new 2007 features.
If you have a lot of workbooks to convert there is an option to switch this prompt off permanently.
Press OK to confirm the conversion.
Once the file has been converted there will be another prompt asking if you want to close and reopen so you can use the new features.

Useful Links

blogs.msdn.com/excel/archive/2006/07/20/671995.aspx - Official Excel blog explaining the new file formats
technet.microsoft.com/en-us/library/cc178998.aspx - Compatibility mode in the 2007 Office system
support.microsoft.com/kb/929355 - How to disable the Compatibility Checker when you deploy PowerPoint 2007 for many users
technet.microsoft.com/en-us/library/cc179188.aspx - Migration considerations for Excel 2007
office.microsoft.com/en-us/excel/HA100778231033.aspx - Office Excel 2007 features that are not supported in earlier versions of Excel
microsoft.com/whdc/xps/default.mspx - XML Paper Specification: Overview
office.microsoft.com/en-us/excel/HA101641791033.aspx - Microsoft Office Excel 2007 top 10 benefits

Other Notes

The following is a very short summary of features that are not supported in older versions:
The workbook contains more than 65,536 rows and 256 columns. This data will not be saved and any references to this data are changed to #REF!
You can create custom international calendar formats, such as Hebrew, Chinese, etc. However, these calendar formats are not supported in earlier versions of Excel and will be automatically changed to Gregorian date format.
Colour and formatting can be applied to header and footer text. This will be displayed as plain text.
Different headers and footers on even pages or on The first page.
Some cell styles and formatting is not supported and will be converted to The closest format.
Contains more font types and you can use up to 512 per workbook. Some fonts will not be saved.
Custom formulas or text in The total row of a table. The data will not be displayed as a table range.
Option to display or hide the header row of a table. Earlier versions have always had a header row .
table styles are new. in earlier versions You could only format a table manually.
Any tables with read-only connections to SharePoint Services List tables will be lost.
Pivot table limits have been increased for example they now support 1,048,576 unique items per field instead of 32,500 in earlier version.
Pivot tables styles and conditional formatting rules will be lost.
You can now sort using custom lists and by specifying formatting information. This will be lost in earlier versions.
Some filtering conditions are not supported in earlier versions
The number of workbook array formulas in now limited by memory rather than a limit of 65,472.
formulas can now contain structured references making it easier to work with tables of data or portions of data.
Named ranges can have names longer than 255 characters in the new version. They will work in earlier versions but will not be displayed in full in the Name dialog box.
You can apply conditional formatting without stopping when The condition is/has been meet.
You can apply conditional formatting to ranges that are not adjacent.
Pivot tables can have conditional formatting applied to them.
Special affects can be added to shapes and graphics (like transparent shadows)
Embedded objects created in The new version cannot be edited in previous versions.
Workbooks cannot be shared among uses who use a combination of new and earlier versions of Excel. To ensure that all shared workbook features are available, you should save the workbook in the Excel 97-2003 file format.
Table Sorting can now have more than 3 sort conditions.
Formulas can now be nested up to 64 levels instead of 7.
The maximum length of a formula has been increased to 8,192 characters instead of 1,024
The maximum number of operands in a formula has been increased to 1,024 instead of 40.
Certain formulas have had their total number of arguments increased to 255 rather than 30 (eg Median).
User defined functions can now contain up to 60 arguments rather than the previous VBA limit of 29.
table filtering on several items can now be done
Improved sorting and filtering - In Office Excel 2007, you can quickly arrange your worksheet data to find the answers that you need by using enhanced filtering and sorting. For example, you can now sort data by color and by more than 3 (and up to 64) l