InfoWorld: Microsoft unleashes Exchange Server 2003

Microsoft Corp. launched Exchange Server 2003 on Tuesday, officially starting its quest to convert the large number of users on the aging Version 5 of the e-mail server software.
The introduction is part of Microsoft’s Office System launch, for which events are being held around the world on Tuesday.
About 120 million people worldwide use Exchange for e-mail, according to Microsoft. The vendor estimates that between 40 percent and 50 percent of those users are on Exchange Server 5, which came to market in March 1997. The introduction of Exchange 2000 Server in October 2000 did not move users to upgrade, largely due to the tough upgrade path. (full story)

My spin: Using Microsoft Outlook alone gives you only a certain amount of functionality, combined with exchange you get the full collaboration, document tracking and other advanced features.