First, Domino 5.0.10 is NOT supported on Windows 2003. The first release that will be supported on 2003 will be 6.0.3.
Second, I wouldn't change the server name, if possible. Install Windows, then install and configure Domino. If you can swing it, down the old Domino server and copy the databases to the new server. Make sure your notes.ini is pointing at the right places and bring the ID over, as well. If you can turn off the old server completely and give the new one the same Windows name and IP address, you won't have to make any changes anywhere. That's always your best option.
If you have to change the Windows and/or Domino name, you will need to issue a "Move mail file" request in the Domino directory. AdminP then moves everyone's home server to the new server based on the criteria you enter. It works fairly well.
This was first published in July 2003