I promoted a 2008 DC at a site about 2 weeks ago. I'm preparing to demote the 2003 DC at that site.
Here's what I've done so far:
Verified it is not holding any FSMO roles
Made the new DC a GC
In the process of transferring DHCP
Installed DNS on the new DC
Verified replication with repadmin /showrepl, always successful
No errors on new DC
Anything else anyone can think of checking before doing the dcpromo on the old DC later this week?