if its a dc then it means after assigning it the ip address of the new building you have to join the existing computers to its domain.otherwise it wont work.
on your 2003 promote 2000 native to 2003
run the following commands on my 2 2003 dc's
adprep /forestprep
adprep /domainprep
adprep /domainprep /gprep
adprep /rodcprep
3.run through dcpromo on my 2008 and leave it to replicate
promote your 2000 native mode to 2003
run the following commands on your 2003 dc's
adprep /forestprep
adprep /domainprep
adprep /domainprep /gprep
adprep /rodcprep
3.run through dcpromo on my 2008 dc
otsile tirelo