Just found this useful little utility on the Microsoft Web Site – It’s a free download that allows you to send SMS messages from Outlook 2003.
You can enter your SMS text within a Outlook-type entry form and have it sent to your mobile phone for delivery through your mobile phone network service. There is no requirement to install third-party software or to subscribe to additional mobile network services if your mobile phone can be connected to your PC. This is typically via an infrared connection, Bluetooth technology, or a USB/serial cable.
The SMS messages can be saved as a draft, grouped, and forwarded like standard Outlook 2003 e-mail.