I've been asked this question quite a few times over the last few weeks - "If we buy Exchange 2003 and a CAL do we need to purchase Outlook 2003 as well ?" The answer is no - you get the right to use Outlook 2003 as part of the Exchange 2003 CAL (see http://www.microsoft.com/resources/sam/lic_cal_exchange_server.mspx) However, if you moved to a non Exchange environment then you would need to purchase the Outlook License. And remember, Outlook 2003 will co-exist with previous versions of Office so you can start taking advantages of things like Cached mode straight away.