When you upgrade to Office 2003, the Office toolbar is removed from your computer and Office 2003 doesn't include a newer version. If you use the Office toolbar you can reinstall it.

Run setup for the older version of Office and choose a custom install and only install the toolbar.

If you prefer to try some newer toolbars, try the TrueLaunch bar. Because I like using the QuickLaunch toolbar, this one is my favorite. Another substitute is the Jet toolbar. You can find it at most shareware sites.