If getting suspicious of the actual hard drive itself, then cloning it to a replacement drive is a very wise move indeed and I do recommend that you do as soon as possible if the existing drive is suspect.
Firstly I will explain what is required in hard ware,
Obviously a new hard drive of the same type, same capacity or greater, same or faster spindle speed, and of the correct type either IDE or SATA. (You can also opt for an SSD drive of the same capacity or greater)
A means of connecting the new drive to a USB connection on the computer. This can take the form of SATA/IDE to USB adapter, reasonably priced from most dealers, or an enclosure or caddy to USB, usually a bit more expensive, or if at some time you wish to work with more than one spare hard drive a hard drive docking station, the last being the most expensive. You can find any of those on most dealers sites.
Next and last is suitable cloning software, Macrium Reflect being the one of my choice, and others, as the free version is more than adequate to do the job.
Once Macrium Reflect is installed, plug in the new and replacement drive and then open Macrium Reflect, it will find the existing hard drive and show you what is on it as far as partitions and basic information is concerned, all you do then is click on the "Clone this drive" button, navigate the system to find the new and at this point external drive, as to being where the clone should go and then click finish.
It will get on with the job from there on. It will take some time to do depending on how much data is on the existing drive it can go for an hour or longer.
Macrium Reflect free version can be downloaded and installed from :-
Be aware that the installer may try to offload junkware along with the installation, you can prevent that by careful reading of every window that comes up and removing ticks from boxes for things such as the Ask toolbar, so called free security scans and a few other junkware or unwanted programs. Where a window offers the choice of automatic or custom install, choose the custom install in order to see and prevent the unwanted junk.
It is unfortunately the case that a lot of the vendors or agents of free software are resorting to this sort of hoistware junk as they are paid to do so by the junkware companies.
I did write a full tutorial for the use of Macrium Reflect to create a clone to another or spare drive complete with screen shots on a different forum which I hope will be acceptable on this site.
The tutorial is here :-
Any further questions please ask.
Edit to add you can find the system product key or COA using this software :-
However I would get the clone done first before worrying about that as when hard drives are suspect, they can fail at any time.
Edited by Plastic Nev, 05 January 2015 - 01:42 PM.