I'm sorry, but I was under the impression that stringing in a new ground was a practice no longer allowed. That is, all conductors had to be in the same cable / conduit.
I remeber this being depicted when grounds were introduced, and I have encountered houses built with a separate ground strung along with the 2-wire romex. Yet, I have heard many assertions that you can't do this any more ... nor can you just tie it to any handy piece of plumbing.
I do see the need for a real ground path, though. Electronic appliances often use the ground path ... either to always have power ("instant on," timers, motion sensors, etc.), or in order for the surge suppressor to work.
