To add the Certificate Snap-in to Microsoft Management Console (MMC) in Windows Server 2003 follow the steps below:
- Click on Start -> Run… and enter mmc
- Click on File -> Add/Remove Snap-in…

- Click on Add…

- In the list select Certificates and then click on Add

- Select Computer account then click Next

- Make sure Local computer is selected and then click Finish

- Click on OK

There you have it, the Certificate Snap-in will be shown. Once you are done using the Certificate Snap-in, close the Microsoft Management Console and choose not to save the Snap-in when prompted by Microsoft Management Console.