Overview
Microsoft® Office 2003 Service Pack 3 (SP3) represents a major evolution in security for Office 2003. It further hardens the Office suite against potential attacks and other security threats. This service pack also includes fixes that have been previously released as separate updates for Office 2003.

You can get specific information about this update in the Microsoft Knowledge Base article (923618): Description of Office 2003 Service Pack 3.

Included in this Service Pack
This service pack includes significant new security updates. This service pack also includes updates previously released for Office 2003:
Office 2003 Service Pack 1
Office 2003 Service Pack 2
Update for Office 2003 (925251)
Update for Office 2003 (924886)
Update for Office 2003 (919029)
Update for Office 2003 (923097)
Security Update for Office 2003 (923272)
Security Update for Office 2003 (924424)
Security Update for Office 2003 (921566)
Security Update for Office 2003 (917151)
Security Update for Office 2003 (914455)
Update for Office 2003 (913571)
Security Update for Office 2003 (905645)
Update for Office 2003 (907417)
Security Update for Excel 2003 (918419)
Security Update for Excel 2003 (905756)
Update for InfoPath 2003 (920103)
Update for Outlook 2003 (913807)
Security Update for Outlook 2003 (892843)
Security Update for PowerPoint 2003 (916518)
Security Update for Publisher 2003 (894542)
Security Update for Word 2003 (917334)
Security Update for Excel 2003 (940602)
Security Update for Office 2003 (936048)

Service Pack 3 also includes stability improvements developed as a result of user input from the Microsoft Online Crash Analysis in Office 2003 and from Microsoft Product Support feedback.

Some of the changes in Service Pack 3 modify the behavior of Office 2003, including changes that disable some features by default and increase control for computer administrators. Changes include:
Office 2003 can no longer open or save certain file formats. For more information, see Microsoft Knowledge Base Article 938810.
MAPI forms do not run in public folders and user folders. For more information, see Microsoft Knowledge Base Article 938816.
Office 2003 can now be configured to allow or deny specific COM components. For more information, see Microsoft Knowledge Base Article 938815.
Some COM components with unusual characteristics may not function as expected. For more information, see Microsoft Knowledge Base Article 938814.
Changes have been made to the behavior of Microsoft Office Document Imaging. For more information, see Microsoft Knowledge Base Article 938813.
Attachments with the .gadget extension can no longer be opened in Outlook. For more information, see Microsoft Knowledge Base Article 938811.
Access add-ins can no longer be configured for use by all users. For more information, see Microsoft Knowledge Base Article 938809.
The Fast Save setting in Microsoft Office Word has been removed. For more information, see Microsoft Knowledge Base Article 938808.
Documents saved in certain formats no longer contain the version number of Office. For more information, see Microsoft Knowledge Base Article 938807.
Certain macros in older Excel file formats have increased security. For more information, see Microsoft Knowledge Base Article 938806.