Migrating DC,DNS & Exchange to new hardware

Hello People,

I have DC,DNS & Exchange installed in the same server . W2k3 & E2k3. Now we are planning to move DC & DNS to a new hardware as well as Exchange to another hardware (both hardwares will be new) and remove the old server which hosted all the roles.
Can u plz tell me wat are the best practices.
First i need to move Exchange?
What should i do with my DNS when i do FSMO role transfer to the new server as my DC,DNS are together?
Do i need to do an FSMO role transfer or seize?

Really appreciate your help.

Thanks
Pree