We have some questions about your software environment that can help to resolve your issue:
What mail client is used for reading e-mails?
Which Service Pack installed on your Outlook 2003?
Actually, we suspect that you just reading these e-mails in mail client (or web mail) with settings set to read e-mails as plain text. In that case you will see text of e-mail as plain text and your stationery as attachment.