DC-to-DC Migration-W2K

Hello everybody,

I am running a w2k infrastructure in my organization with an exchange 2000 server. I also have a dc acting as DNS, DHCP, Terminal Licensing & Services, AD, File and Print Server. As this DC is old I have built a new server and am planning to migrate everything from the old DC to the new server and make it the PDC. How do I go about it and will the users be affected while I do the FSMO roles transfer? Becase, if something goes wrong I should be able to fall back onto the old dc. Any advise would be greatly appreciated. Thanks