Digital river's link goes to a info thing for win 8.
I got the PC from a guy who has some sort of business with PC's. It was one of the business licenses I believe.
In that case, you need to clarify with the guy you bought it from whether you've got a legal license or not. If yes, then he should be able to provide you with a physical disc or ISO image. If no, then you're SOL unless you want to resort to channels that we aren't allowed to discuss here.
If the world isn't making sense to you, you're either drinking too much or not drinking enough.