It is not clear just what has been done. Assuming I got part of what the post says, a new computer with no OS has been completed and Windows 7 upgrade 64 bit install has been attempted but the product key is not accepted. Also assuming the product key in question is the one for Windows 7, Make sure the key is for the version of windows 7 IE: install is Home Premium and key is for Home Premium. BTW: key will work for 32 bit or 64 bit. Take a look here:
http://www.winsupersite.com/win7/clean_install_upgrade_media.asp
If the error code/message is like the one shown, then the answer on how to fix it is there, also. Hope that helps.