Just in-case you haven't already read about the fundamental change
to the Exchange/Outlook 2007 CAL licensing, it's worth covering here..
unless you were on Exchange Server 2003 with Software Assurance at 30th
November 2006 you will not be able to automatically use Outlook 2007
when you upgrade to Exchange Server 2007.
prior versions, Exchange Server 2007 Standard or Enterprise does not
include the right to install Outlook on devices for which CALs are
obtained. However, for each Exchange Server CAL, Core CAL
Suite or Enterprise CAL Suite with active Software Assurance coverage
as of November 30, 2006, customers will be granted one Office Outlook
2007 license. The right to use Outlook under that license expires upon
expiration of the corresponding CAL. Use of Outlook under this offering
is subject to the customers license agreement and the product use
rights for that product. If Software Assurance coverage on the
corresponding CAL is maintained continuously (i.e., renewed with no
lapse in coverage), and one later version of Office Outlook (i.e., N+1,
where N=Office Outlook 2007) is made available prior to the expiration
of that coverage, customers license will be for that version instead.
Alternatively, customers are eligible to acquire Software Assurance
coverage for that Office Outlook license, provided that coverage is
acquired by February 28, 2007. Customers who wish to acquire Software
Assurance coverage for Office Outlook after that date must first
acquire a new license for the version of Office Outlook that is current
at the time coverage is acquired. “