Do you need to run ADPREP if you already transferred FSMO roles from 2003 server to NEW 2008 server

I have an exsisting 2003 DC. I have a brand new 2008 DC (which is also a virtual machine.) I did the transfer FSMO roles from the 2003 server to the 2008 server. I have also moved DNS and DHCP services over. The only thing left on the old DC is moving the files over to the new file server. (old DC was also the file server)

Do I need to run ADPREP if I already transferred the roles?

Do I need to seize FSMO roles on the old DC?

DO I need to run dcpromo to demote the old DC? (This server will be wiped clean for something else.)

Or do I just stop services on the old DC and the new one should take over?

THanks for your help.