Your network contains an Active Directory domain. The domain contains a Lync Server 2010 Standard Edition server and a server that runs Microsoft Exchange Server 2007.
All client computers run Windows Vista Service Pack 2 (SP2).
All users use Microsoft Office Outlook 2003 and Microsoft Lyric 2010.
Users report that they are unable to use the Outlook integration features.
You need to ensure that the users can use the Outlook integration features.
What should you do?

A.
Upgrade all client computers to Windows 7.

B.
Upgrade the Exchange server to Exchange Server 2010.

C.
Install Outlook 2010 on all the client computers.

D.
Deploy the Exchange Server 2007 Unified Messaging server role on the Exchange server.

Explanation:
http://technet.microsoft.com/en-us/library/gg412817.aspx