How to install Equation in Microsoft Office 2003

To resolve this problem, use Maintenance mode to install the Equation Editor to your computer's hard disk with the Run from My Computer mode.

To Install Equation Editor in Microsoft Office 2000, follow these steps:

1. Quit all programs that are open.
2. Click Start, point to Settings, and then click Control Panel.
3. In Control Panel, double-click Add/Remove Programs.
4. In the Add/Remove Programs Properties dialog box, click your Microsoft Office 2000 installation, and then click Change.
5. In the Microsoft Office 2000 Maintenance Mode dialog box, click Add or Remove Features.
6. In the features tree, click the plus sign (+) next to Office Tools.
7. Click the arrow next to Equation Editor.
8. Click Run all from My Computer.
9. Click Update Now.

ref: http://support.microsoft.com/kb/228569