- Click the “Start" menu and point to “All Programs." Click “Microsoft Exchange." Click to open “Exchange Management Console."
- Click “Configuration" in the left pane root menu.
- Click the “File" menu from the top bar and choose “Properties" to open the Properties dialog box for the Configuration container.
- Click the “Service Account Password" tab.
- Type the new password. Retype the new password to confirm.
- Click “OK."
Read more: How to Change the Exchange 2003 Service Account | eHow.com http://www.ehow.com/how_8401396_change-exchange-2003-service-account.html#ixzz1Tqv1aDNz