The issue of the inability to open AD RMS protected documents with Microsoft Office 2003 has been resolved with a hotfix. You can obtain the hotfix at the following locations:
Office Client – KB978551
Word Viewer – KB978558
Excel Viewer – KB978557
Update (2/10/2010) - We recommend that AD RMS users download and install the update for AD RMS clients. If you have this update, the hotfix for Microsoft Office 2003 is not necessary.