I have purchased Windows 8.1 Pro 64 bit retail license (purchased retail key and downloaded from MS website). Recently my primary boot drive has started showing SMART failure and showing some bad sectors. I need to change the drive as soon as possible. I will have to install a new hard drive and install Windows 8.1 a fresh. Now how can activate the copy on new drive? Is there any way to deactivate the first installation and reactivate the second? Thank you all. Please I need to know ASAP.