How to change Win 7 Activation from MAK to KMS?

Three of our shiny new Win 7 workstations had to be activated using a MAK key and I'd like to revert these machines to KMS. Can this be done painlessly? Effectively I want to revert the machines back to an unactivated state, remove the MAK key and let them then find our KM Server.

Is there a way of doing this that doesn't involve a reinstall of Windows? I've tried rerarming the machines but that doesn't work.

Presumably it's a registry edit job but I can't find anything on Google.

Can anyone help?

If you run sysprep it will unactivate them.

Can you not change the key when you right click computer > Properties?

OK, I'll try sysprep, thanks.

Yes, can change key in properties but don't you need then to enter a VLK? We don't have one.

There are generic VLK keys you enter for use with KMS. You will find them about 1/2 to 2/3 of the way down this page. The page also describes how to use the slmgr.vbs script included with Windows to manage the entire activation system, including switching from MAK to KMS.

Thanks for that AT. That worked.

I had already tried this method but it failed, the reason it failed was that MS support gave me an incorrect key! It worked fine with the key from the page in your link.

All the best.