Why not Qxf3 here?

My (limited) chess knowledge tells me I should take on f3 with the Queen in the diagram below, to avoid a double pawn, by capturing with the g-pawn. But my new toy, Stockfish (at 20 ply), gives the position after Qxf3 a score of -0.32, and +0.08 after gxf3. Is Stockfisk drunk, or are there good reasons for not capturing with the Queen, although it gives a double pawn? 

How you going to get back to protect the pinned knight once black takes pawn on B4??

yes...a very good reason.Qxf3 allows Bxb4 and the only way to save that knight is for the king to lose it's right to castle with Kd2.it can get a mess in a hurry if black chooses to take that knight in which the king will have to go to c3...such outtings for the king in these positions can be dangerous...hence why gxf3

see just beat me a few more games...I'll teach ya lol

I have Stockfish too cigoL and Qxf3 is the best move. gxf3 does not show a +ve score. Either way it looks ugly for white.

Thanks everyone! 

I'm glad that my own judgment (to play Qxf3) is the better one.  And it turns out my Stockfish was drunk, or rather was affected by a heat stroke. Now, when the PC is cooled, the score is very different: Qxf3 (-4.48), gxf3 (-5.33). Both at 20 ply. 

Maybe it wasn't because the PC was overheated. It could also have been me doing something wrong. Anyway, problem solved. 

I wonder how evaluation defers from one programmer to the other? It should depend highly on the opinion and knowledge of the program developer. So, why do you rely so much on chess software??

AnthonyCG, I'm running this thing on a silly MacBook Pro 3 GHz Intel Core2 Duo, now on a table with a fan build in.  But this machine is way to slow, and I'm actually looking to buy a PC for only chess analysis. But it's a jungle out there! 

I'm even thinking about building a cluster. 

James_Bond_Fan, who is relying so much on chess software? 

You are not a computer

You are not a computer

You are not a computer

Arctor, if this is addressed to me, you are correct. But what's your point? 

My point is that even if a computer thinks that one move is objectively better than another, it doesn't mean that the resulting position is easier for a human player to play (I'm talking in general terms)

As for that position, 1.gxf3 Bxb4 2.Qd2 Nd4 with the threat of Nxf3 puts White in a very uncomfortable position when he has to move his king anyway, so 1.Qxf3 looks better to my human mind at least.

It seems you're getting very comfortable with your new friend stockfish (and he's lying to you!!). I worry that it might hurt you in your quest for mastery. I'm nowhere close to a strong player but I've never used computers very much and reckon I'm better for it

Yes, that is a bit puzzling...

Pawns are like kids they never listen....probably just ran across the street on its own

Figured if it just snuck up on the big guy in the funny hat it could munch him and nobody would even notice...

That sure does look like a pawn hat.  You could wind up being a Pawn Star :)