Could tell me why it is there then? I always thought it is the key, but reading through OEM project really could not understand why they give a key that is not used.
I am going to follow the advice from the experienced people whom kindly helped me, making recovery DVDs from inside Windows then go for a clean install of a different version. But this discussion, I think, is a good chance for me, maybe others to learn.
I have made the recovery DVD's and downloaded and installed Windows successfully. I appreciate every contribution from you all to help me and my issue is solved. Thanks to everybody.