660 SLI or 120 HZ MONITOR ?

Hello there , I was wondering if u guys can give me an advice about upgrading : firs here are my specs

Mobo : Asus z77 p8 v pro Deluxe

CPU: intel i5 3570k 3,4 ghz ivy

Mem : 8gb 1600 mhz corsair vengance

GPU: sapphire HD 6950 2GB

PSU : 750 watt Cougar

i have samsung b2330 monitor 23inch 1080p but with 5ms response

So here is my question  

Would u prefer to get 660 SLI for this setup or 120 HZ Monitor , aslo keep in mind that only available monitor for me here in market is SAMSUNG SA23700 D 3D would this monitor exhaust my Card in term of 120 HZ that will be tearing in games like BF3

thanks guys   sorry for my bad english