Security enhancements, improved stability and performance...
New in Office 2003 SP-3: Office 2003 Service Pack 2 (SP-2) contains security enhancements and stability improvements for Office 2003, some of which were previously released in separate updates. Office 2003 SP3 combines the previously released fixes into one update. An extensive list of enhancements, security patches, and bug fixes can be found here - Last Updated: 09.19.07 Upgrade Meter:2
New in Office 2003 SP-2: Office 2003 Service Pack 2 (SP-2) contains significant security enhancements, bug fixes, and stability and performance improvements. SP-2 also adds a Phishing Protection feature for Outlook that filters out e-mails crafted to steal personal information. The service pack additionally combines some of the previously released individual Office 2003 updates into one update. A more extensive list of enhancements, security patches, and bug fixes can be found here - Last Updated: 09.28.05 Upgrade Meter:2
New in Office 2003 SP-1: Office 2003 Service Pack 1 (SP-1) contains significant security enhancements, bug fixes, and stability and performance improvements. SP-1 also includes many performance and feature enhancements to Microsoft Office InfoPath 2003. The service pack additionally combines some of the previously relesaed individual Office 2003 updates into one update. Specifically, the Office 2003 SP-1 includes the Excel 2003 Update (KB834691), the Office 2003 Critical Update (KB828041), and the Word 2003 Update (KB830000). A more extensive list of enhancements and bug fixes can be found here.
Upgrade Meter:2
Pros: A helpful collection of enhancements and fixes for users of Office 2003
Cons: Not necessarily must-have upgrades for most users