Building a seaprate Exchange 2010 in the same domain where an exchange 2010 server exist.

Hi...I need guidance from you experts on how to make my plan happen.. Here's my scenario.  We are in the process of migrating the whole enterprise into Exchange 2010.  Currently, we have a single "top" domain (called "corp") and to sub domains below them.. ("east" and "west").  each domain has their own exchange 2003 server (we recently migrated off from Exchange 2000).the "east" domain has an Exchange 2010 server co-existing with Exchange 2003.  the exchange 2010 only has the IT department folks in it and it is used as a "test"environment.  To roll Exchange 2010 out to the "east" domain, we would like to create a new Exchange 2010 environment within the same "east" domain.  I want it separate from the "test" environment.

the "test" (exchange 2010) environment has 3 servers (1 for CAS and HUB, 2 MBX server).  Each mailbox server has 2 mbx databases and they are in a DAG.

how can i build a new Exchange 2010 server environment within the same domain and create its own DAG.?  It seems straightforward.. Build a CAS and HUB first, then build 4 MBX servers and put them in a DAG.  migrate the mailboxes from the existing Exchange 2010 and uninstall that "test" environment.. This NEW exchange 2010 environment will be the final step in migrating my users from Exchange 2003.  when the "east" domain is complete. the "west domain will follow suit.

I know Exhcange 2010 relies heavily on AD and that should make iunisntalling or decommissioning  the "test" environment painless..  is it really this easy?  I could use tips and the "proper" way of making this happen.

thanks in advance.... Jay