Windows XP product type and key

I buy an Lenovo with Windows.
The pc come with Windows XP type and key.

But few months ago, I send my pc to repair.
The tech at my company reimaged my PC with a corporate key product (new type and new key).

Yesterday, I tryed to upgrade this PC to Windows 7 (Windows 7 upgrade version).

First, I tryed with a clean install on a new HD (because I just buy a new one for that and because I don't want to use it on the corporate key). The key refuse to activate since WinXP aren't on the disk.
It's ok... (Did someone know where to put old windows xp info for Windows 7 upgrade?).  

Second, I tryed to install a new windows xp with the windows xp disk I had. This basicly not the same product type so he refuse my key.

I tryed many cd-key changer (offline since I don't trust them at all) but since the product type is not the same.. the key is not good.

So... can I change my windows XP key and product type ?  

So basicly I have 2 legit cd-key... windows XP key and Windows 7 upgrade key but I can't UPGRADE!!!!!  

So I resume:
1. In Windows 7, did someone know where to put old windows xp info for Windows 7 upgrade? (since I don't have the windows xp with the good product type for accepting my key) ? for activate it.

2. Can I change my windows XP key and product type ? Look like it's in regedit LOCAL_MACHINE\Software\Microsoft\Windows NT\current_version\
but I don't have the Hex code required in there.

3. I'll try to find on Lenovo the restore disk... since I doesn't have one.
Did someone have the link ?

Thank you very much.