I need to change this setting in administrative tools->local security policy->local policy->security options->Accounts: Rename Administrator Account on about 450 machines. Anyone know of a way that I can automate this? Thanks for your help.

maybe you could use ghost make a clone for one machine that recover on the others.

Are the machines already deployed? Or are you just setting them up?

All the machines are deployed unfortunately and have been in use for a while. Many of the users do not understand the use of network space so I cannot reimage then all unfortunately. Basically they want me and my team to go through two fifteen story buildings and change one option on each machine.

My first guess would be to find that reg key and propagate the modified key to each user's registry.

I changed the value and tried to search the registry for it but was unable to find it. Tried it again just now to make sure it wasn't a pebkac error and still no luck.

Are these machines part of an AD. I believe this is a group policy setting that could be pushed out from the server? I'm not positive though.

The machines are not part of an AD unfortunately.