I just got my first 660TI sc today. I was using an XFX 7770 Black Edition in xfire. Long story short too many problems with the cards working togather.  I am praying that this card will be a big improvment for me. Can anyone tell me if there is a weak spot in my system? or a sugestion to change anything. Everything is running stock settings.
 
 
My system:
Gigabyte ga- z77x-ud5h
I-7 3770k
Corsair GS 700w psu
corsair vengance 16 gigs@ 1600
corsair H100
corsair Force 3 120gig ssd
WD green 1 terebit for storage
LG bluray burner
Corsair 600t case
New Evga GeForce GTX 660 Ti sc

only thing Im seeing is no free games for me. I returned the other XFX and got this. Now Im seeing the promotions but only online. oh well thats not a solid reason to buy a gpu
 

Welcome to Team Green 
Steam allways has sell's on it so check it out who know's you may get a game for next to nonthing.

Yes 660TI in SLI should out performed a single 670/680 card 

 
Looks like a winner to me. Also it was a good choice going with Nvidia.       

Yeah well not to disappoint you, NVIDIA has nasty driver issues too, the same AMD has no difference there.
Just telling from my experiences, the famous Black screen NV driver has Crashed crashes have bugged me many times 
 
You just should know what driver you should avoid and you can only do this by finding out by testing them. I know people that Use Radeons and don't have a single problem, the same I know People with GeForces that don't have a single problem, but I also know the ones that have major issues with both.
 
So to be honest Radeon or GeForce it does not really matter, they both have issues they both can rock too. No need to choose sides I'm like
 
But I think you will see neat improvements as the specs go  I think you are gonna love this setup, it's all about the improvements right !

Congrats, the system looks nice.