Microsoft Office 2003 Service Pack 2 contains significant security enhancements, in addition to stability and performance improvements. Some of the fixes included with SP2 have been previously released as separate updates. This service pack combines them into one update.
You can get specific information about this update in the Microsoft Knowledge Base article (887616).
WHAT’S NEW IN VERSION SP2
How to Register Software With a Registration Code?
-Double-click the desktop shortcut to launch the .exe file.
-Enter your name and the .exe Registration Code precisely as they appear on your registration acknowledgement email when the registration reminder window appears.
-Press Register. Enter all additional details exactly as they are listed on your registration confirmation email, including your .exe serial number.