Unless you are living under a rock, you've heard that Office 2003 SP2 came out last week. Home users and those not using it in a corporation should install the update over the next week or so. If you use Microsoft Update, SP2 will be installed automatically within the next few days, if it isn't already installed. To check, go to Help, About and check the build number. It will say "Microsoft Office Outlook 2003 (11.6568.6568) SP2" if SP2 is installed.
If you aren't using AutoUpdates, you need to go to Office Update – accessible via Help, Check for updates and download it. While you can download the patch yourself, using one of the update services will insure you install the correct version.
Outlook Live users should use Office Update or Microsoft Update to insure it downloads the correct version.
If you are using Office at work, you should not install patches or service packs unless told to do so by your administrator.
Issues that are fixed in Outlook 2003 by Office 2003 Service Pack 2
Description of Outlook Live 2003 Service Pack 2
Information about SP2, including any issues that might arise as it gains wider usage:
Published October 4, 2005. Last updated on July 3, 2012.