Puzzle of the week #85

Chess Diagram: 

[Event "Puzzle #85"][Date "2009.09.04"][Result "1-0"][SetUp "1"][FEN "8/2rb4/4k2p/P2p2p1/1N1Ppp2/7P/5PP1/1R3NK1 w - - 0 41"]

I just want to prove you that I also do in my games what I teach you. Maybe you've heard the saying
"Do what the preacher says and not what he does"
I am not a preacher. It could be a bit hard for you to understand now; you'll understand it for sure later on in life. Anyway, going back to doing what I say, this week I would like to talk about winning a game where you have advantage as fast as possible. Why do you need to do that? Well, you need to do it for a few reasons:
a) Don't spend extra time and energy you will need in your following games
b) Finishing your game faster gives you time to relax between games
c) Last but not least you get the win! It is important to score the win and I say this since quite a few times I did the opposite, wandering around with my pieces, hungry to capture more of my opponents' pieces just to end up in a draw, or worst losing those games
In order to prove it, please see above position from a game I just finished at Gameknot, game Valer Eugen Demian (CAN) - C. Bariloche (ARG) White has managed to win a piece and now all needed is to bring home the point as soon as possible. Your task:
a) White to move and win as soon as possible
b) Explain your solution
c) After you read Rick's solution and my observation below, please answer the bonus question: what other piece is needed on the board for 2 Knights to mate the lone King?

Total available points for this puzzle is 25. The answers will be published next week together with puzzle #86.

Puzzle #84 solution:
Today we are enjoying again Rick's solution:
a) To prevent myself from promoting, I tied my hands together (it hurt!). White has 2 extra Knighs in the endgame, but one is under attack and the other is too far away. White's King isn't on a favourable spot either. With such misplaced pieces, White actually finds a winning line: see solution
b) What tactical elements did white use to win? White's 2 main elements were forks and skewers. He threatened numerous forks at the beginning and finished Black off with skewers (diagonal and straight). It's fishy how everything works out coincidentally for white LOL

Would like to add up just one small observation for you guys to remember:
2 Knights cannot mate the lone King! In other words White had to be very careful not to exchange Queens.

[Event "Puzzle #84"][Date "2009.08.28"][Result "1-0"][SetUp "1"][FEN "8/4N2P/K7/8/8/k7/N3p3/8 w - - 0 1"]1.Nb4!! {If Black promotes then Nb4-c2+ is a family fork and Kb3 is met with Nd3} 1...Kxb4 {How the position has changed in 1 move! Playing Nb4 drew the Black King within range for White's pieces to actually do something} 2.h8=Q e1=Q 3.Qb2+ {Here Black has no fewer than 3 escape routes, but they all lead to defeat} 3...Ka4 (3...Kc4 4.Qb5+ Kd4 (4...Kc3 5.Qa5+ {White wins}) 5.Nf5+ Ke4 6.Qe8+ {White wins}) (3...Kc5 4.Qb6+ Kc4 5.Qb5+ {Same position leading to a win for white}) 4.Qa2+ Kb4 5.Qa5+ {White wins}

Correct solutions:
Rick, James, Jeremy - 20 points
Owen, Andy Q - 14 points
Wilson - 5 points
Alex Ge - 12 points for puzzle #83

Andy Q - 145 points
Rick - 135 points
Jeremy - 88 points
Joshua - 71 points
Wilson - 54 points
Alex Ge - 51 points
Owen - 48 points
James - 43 points
Karl - 39 points
Katerina, Andy Y - 20 points
Marcus - 19 points
Nathaniel - 18 points