I don't think I was clear and should clarify. I was talking about buying one of the adaptors made for doing just what I am suggesting. The ones that take a 3 prong plug on one side and 2 prongs and a green wire with a lug on the other end. The green wire is susposed to be connected to a ground. I was just suggesting getting that ground from across the room. Also, you should not plug anything in until all the grounds are securely connected.

I would strongly advise against opening the outlet box and fooling with the wires inside.