Yes, here are some details from the Communicator 2007 Testing Guide:
Communicator 2007 Compatibility List
|
Operating System |
Outlook Version |
Exchange Server Version |
|
Windows Vista® 32-bit (RTM) operating system |
Microsoft Office Outlook® 2007
Outlook 2003 SP2 |
Microsoft Exchange Server 2007
Exchange Server 2003 |
|
Microsoft® Windows® XP Professional with Service Pack 2 or later |
Outlook 2007
Outlook 2003 SP2 |
Exchange Server 2007
Exchange Server 2003 |
|
Microsoft Windows Server™ 2003 with Service Pack 1 or later |
Outlook 2007
Outlook 2003 SP2 |
Exchange Server 2007
Exchange Server 2003 |
|
Windows 2000 Professional with Service Pack 4 or later |
Outlook 2003 SP2 |
Exchange Server 2007
Exchange Server 2003 |
You may potentially see alerts or errors with Presence information in Outlook 2003, but not necessarily. Search the forums here to find out about some of the issue some users run into. Other than that it is supported and there is no reasons to hold off an OCS deployment until upgrading clients to Office 2007.
