Upgrading PC with Win7 key used in other PC?

I have two Windows licenses: WIndows 7 Home that was already installed on this HP and Windows 7 Ultimate that I had purchased and is currently installed on a Dell. I upgraded the OS on the HP to Ultimate (through the MS site), but it currently is not accepting my activation code probably because it's being used on the Dell.

Two questions:
What do I need to do to be able to 'transfer' the Win7 Ultimate activation code from the Dell to this HP?
How do I retrieve the Win7 Home key used in the HP so I can use it on the Dell?

I also tried finding Microsoft contact information, but that's a rather impossible task.

Thanks.

If any of them are OEM licenses you can't move them from one PC to the other. OEM once installed and activated is tied to the hardware/motherboard in the PC it was activated on. Retail copies can be moved from one PC to the other but only activated on one PC at any one time. This > Keyfinder | Magical Jelly Bean should retrieve your product code for you.

Thanks for your reply.

Neither of them are OEM.

I ran the keyfinder on the HP (the one that had Win7 Home and upgraded to Ultimate via microsoft site) and the CD key it gives me is the one from my Win7 Ultimate copy. But this key is the one being used for my Dell.

What can I do? Did the upgrade to Win7 Ultimate from the microsoft site delete my previous product key?

Thanks.

It's stored in the registry and is encripted. The prevoius one was likely replaced by the upgrade key. It over wrote the other key. Isn't there a COA sticker on the PC with the product code on it?

If there is a COA sticker on the HP then it is factory OEM which cannot be moved from that machine anyway.

If it is retail which can migrate you should have your Product key on an insert which came in the retail packaging.