I'm not sure what you mean you "quadruple checked". I'm thinking 1) visualize it in your mind 2) use the analysis board 3) ask your friend who is a master 4) put it into Rybka. Of course I'm kidding! (the last two would be cheating and I know Erik's not a cheater)
Very nicely played by white!
In this game my opponent made a mistake... and then I almost overlooked checkmate because I thought it was too simple!