A retail key would not be stuck on the side of the computer - it comes with the retail packaging.
An OEM key is stuck to a COA label on the outside of your computer and is VERY difficult to remove without damaging it.
You will note that the OEM product key specifically states OEM on the label, yet you say the keys came off old computers, but you have no way of telling which keys they are.
Are you sure they are genuine keys? Perhaps you'd post a screenshot of them so we can tell exactly what they are.
Once we know that, we can give you the correct help.
However, I repeat: if they are OEM product keys they cannot be used on another computer. They are tied to the computer they were first installed on and die when the computer does.