I have just finished some of small projects installing exchange 2007 servers into existing Exchange 2003 environment. Implementing exchange 2007 is fairly simple and fun. It is a lot different for exchange administrators, and somehow I see the challenge on the administrator faces. Users look to me are so happy with new OWA 2007. It is absolutely stunning. Users seem to like the new OWA and outlook 2007.
Microsoft Exchange Server 2007 does not support an in-place upgrade from any earlier version of Exchange. The Exchange organization must be operating in native mode before you can start introducing any Exchange 2007 servers into the environment. This means that only Exchange Server 2003 and Exchange 2000 Server servers can exist in the organization. If your organization includes Exchange Server version 5.5, you must perform an upgrade to Exchange Server 2003 or Exchange 2000 Server before moving to Exchange 2007. To move messaging services and data from Exchange Server 2003 or Exchange 2000 Server to Exchange 2007, you must use the move mailbox functionality in Exchange 2007.
Moving mailboxes from exchange 2003 to 2007 is very easy task. While we were moving mailboxes we had an issue with RUS was not stamping exchange 2003 server. Rather than taking time and going through those entire trouble shooting steps we ended up creating users on Exchange 07 and moved them back to the Exchange 03.
If you have not read the article Good bye RUS here it is. The key change is in exchange 2007 the subservice is removed. Recipients are fully provisioned as they are created.
Below is taken from the article "Good bye RUS" we won't miss you forever. (- :
The RUS has always been a bit of a black box for administrators. When it works, it's great. But if it ever stops working as expected, it is quite difficult to figure out what's wrong. Worse, since the subservice processes recipients asynchronously, it is difficult to determine whether the subservice is "not working", or simply "working slowly".
The advantage of bringing the stamping of recipient objects into the Cmdlets as a synchronous operation extends beyond troubleshooting, however. Even in the case where the RUS is working as expected, moving this functionality into a synchronous cmdlet execution allows for "instant on" recipient provisioning and faster service.
With Exchange 2007, you can immediately use a mailbox once the mailbox is created. No need to wait 5 minutes for the RUS to stamp the object!