The compact disc that accompanies the Microsoft Exchange Server 2003 Administrator’s Companion is a 120-day trial software version of Exchange 2003 Enterprise Edition.
If you plan to upgrade from Exchange 2000 Server to Exchange Server 2003, you must install Exchange 2000 Service Pack 3 (SP3) before installing Exchange 2003.
Actual requirements can vary based on your system configuration and the features you choose to install.
Exchange 2003 Standard Edition System Requirements
Intel Pentium or compatible 133-MHz or higher processor
Intel Pentium or compatible 550-MHz processor ...