Question : Upgrading from server 2003 domain to server 2008.

I have asked some questions about the best way to upgrade our Domain in the past.  I currently have 4 server 2003 DC's running on VMWare.  We decided to create new VM's promote them and then to Demote the old ones one at a time.  I have created the first server 2008 R2 Server and I am ready to promote it.  

I am not sure what to expect once I promote it.  Will our AD scheme change once I introduce the new server 2008 R2 as a DC?  

I understand that before I start to demote the 2003 DC's that I will have to make sure that the roles are moved from those.

Obviously I am a little nervous about this move.  I am hoping someone can explain what will happen and what steps I will need to take once I have promoted the new DC to make sure that the AD scheme stays the same except for the new GP options that should be available at that time.  Will I have to make changes on the 2003 Server AD schemes to be compatible with the 2008 AD?

Answer : Upgrading from server 2003 domain to server 2008.

when you install a 2008 DC you are changing the schema at that time, but you won't be breaking anything...the existing 2003 DCs can exist until you move the roles off of them and demote them (whenever you're ready). This is because you won't be running AD in 2008 mode yet. Once you're running only 2008 DCs then you can choose to raise the domain functional level to 2008 and you'll see more new features.

here's a good doc on functional levels and different versions of DCs....

http://www.petri.co.il/understanding-windows-server-2008-active-directory-domain-and-forest-functional-levels.htm