1. Open Excel 2003 and select 'Tools' on the menu bar. Select 'Customize.' The Customize dialog box appears. Click the 'Toolbars' tab. Select 'New.' The New Toolbar dialog box appears. Type a name for your new toolbar and click 'OK.'
2. Review your new floating toolbar. Click the 'AutoSum' button on the standard toolbar to reveal a drop-down list of functions. Click 'SUM.'
3. Drag 'SUM' from the standard toolbar to your new floating toolbar. Click 'Close' to close the Customize dialog box.