Yes, Enterprise has no other editions and isn't even considered a normal retail Win7 installation. I don't know why you told me you have Ultimate to unlock, since I could have told you this earlier to save time.
You'll need to locate a Win7 retail installer with any normal version to unlock.
I don't believe their are many enterprises that have bought a legal Windows 7 Enterprise are going to be using Gregs tutorials.
They will be using their I.T. department or paid consultants to do their installs and activations.