Need to migrate an acquired Active Directory Domain into ours

After an Acquisition we now need to migrate the new Active directory domain into ours. We already have a data connectoin between the two offices but they are working completely independently with their own exchange email, active directory system, file sharing system, etc. The new office is running Domain function level 2003 and we are running domain function level 2008r2. I have already built a physical Windows 2008r2 server that I plan to drive up to the new office and install it as a DC that doubles as a file server. I know I will have to set all the workstations to log into our domain. I need all advice, scripts and ariticles that may assit me with this project. I know acquistions are fairly common these days and am hoping there are pre written scripts and procedures that may help me with this process. Exchange will have to be migrated over from their Exchange 2003 to our Exchange 2007, but that may be a question for the exchange section of EE. All advice on active directory migration is appreciated.