Sorry if this has already been addressed but I just finished reading an article that you can't run a version of Outlook older that Outlook 2003 SP2 and connect to Exchange 2010 do to the MAPI encryption requirement of Exchange 2010. Is this correct?

To run Outlook 2003 against Exchage 2010, you need to disable the RPC encryption requirement to make it work:http://support.microsoft.com/kb/2006508Outlook connection issues with Exchange 2010 mailboxes due to RPC encryption requirementhttp://technet.microsoft.com/en-us/library/ee332317.aspxUnderstanding RPC Client Access

You should also consider the issues mentioned in a thread I started here -http://social.microsoft.com/Forums/en-US/partnermsgexchange/thread/26f6ecb2-3b69-4997-b4e7-d3c5afad5ff2If you are using Outlook 2003 without Cached Mode then by default you can end up waiting for about 60 seconds for the view to refresh after a deletion or move of any Outlook item including messages, contacts, etc.For anybody running Outlook 2003 on a terminal server will know there is no cached mode available and therefore no solution to this problem. It seems that support for Outlook 2003 has not been properly thought through by the product teams.Bob

It has taken Microsoft about eighteen months to resolve this Exchange 2010 Outlook 2003 incompatibility - http://support.microsoft.com/kb/2009942 There have also been Exchange 2010 throttling issues which caused Outlook 2003 users pain when opening other user's calendars or folders - http://support.microsoft.com/default.aspx?scid=kb;en-us;2299468&sd=rss&spid=13965 Also take a look at http://www.wardvissers.nl/2011/02/21/exchange-2010-opening-multiple-shared-calendars-additional-mailboxes/ which additionally gives details of the Exchange 2010 sessions per user and maximum allowed service sessions per user limit. Good luck! Bob