Adding temporary second domain controller

I want to migrate from Windows 2008 32bit to Windows 2008 64bit in a single environment, that needs a clean install where the PDC machine is currently having file sharing, active directory and DNS role. I think that I can install over top of the current OS and rebuild the file sharing systems, but I dont want to lose all my users and AD objects. So, I have build a secondary machine on Windows 2008 32bit and promoted it to AD and also installed the DNS role. If I am going into the AD MMC snap-in, then its listing all my users as I expect. If I do a clean install now on my primary machine, then will I be able to run DCpromo and point to my new secondary computer to rebuild the AD tree? Or should I set the properties of the operational masters so my secondary machine which is the operational master and if so, what are the implications for my domain users? Thanks for any information.

Initially, there is no doubt that clients are configured to use the second Domain Controller as a DNS server in addition. Subsequently, you have to ensure the event log and dcdiag to observe whether the whole thing is running effortlessly. And after that, transfer the FSMO roles in the direction of the second Domain Controller. If that was working and you perceive them resting on the second Domain Controller as soon as running "netdom query fsmo", move down the first Domain Controller with dcpromo, flatten the box, reconstruct it and re-promote it toward a Domain Controller. As a suggestion, leave mutually DCs running. You are suppose to include two DCs for each domain for redundancy intention. I hope this will help.