Win XP question Product Key

I have Win XP Pro Corporate version (FCKGW-) and I want to change the product key to a legal version (change registration without a reinstall). I have tried all the methods I can find but no success. I tried the registry change, then start Activation program (as outlined by Microsoft). I can change the oobetimer in the registry, but the activation program will not start in order for me to change the product key. The activation window will never open.
I have also tried the direct change programs without success.
I can change the product ID, but not the product key.
Any ideas?
Thanks.

 

You will have to upgrade with a retail copy of XP.

A Volume license copy of XP will not accept a Product Key change to a retail key.

VLK accepts VLK, OEM accepts OEM, retail accepts retail.

The key must match the version.