Resigning when you shouldn't. Who would win?

I played this game as black today thinking that it was a winning position, however the more that I look at it I realize there seems to be no way for me to stop white's promotion threat. Luckily, black resigned due to the frustration of losing his rook in a pin I salvaged from the wreckage. It seems that the psychology of the game really effects the outcome.

So, my point in posting this is to ask first who is winning?

Second, to show that you should really look before resigning.