I need to find a better way to change thousands of computer names

Hi all,
We had a huge re-org and thousands of pc's need to have their names changed.
I created 2 exe's that sort of automate the process. There are 2 exe's because the are 2 reboots in the process of changing the name. (i.e. kick the pc off the domain, rename it, reboot, log back in add it back to the domain and reboot)
(I used NetUnjoinDomain, SetComputerNameExA and NetJoinDomain)

Is there a way to do the above procedure all in one shot?? say by hacking the registry maybe?
I searched the registry for the computer name and I found it all over the place.
Is there a main key to change? Or do I have to change all of them?

All the new computer names already exist in Active Dirctory.

Please advise,