120hz Monitor OR CPU(+mobo) upgrade?

I cannot decide whether to upgrade my cpu and mobo or to upgrade my monitor.

I will be buying a GTX670 and a Corasair AX750 together with either cpu and mobo or monitor.

CPU planning to get: i7 3770k
Mobo " " ": Asus P8Z77-Pro
Monitor " " ": BenQ XL2420T

I will be mostly gaming. Titles like BF3, the coming Medal of Honor, GTA just generally FPS and some racing. And with light to medium video conversions.

Current CPU: C2Q Q8300 2.5ghz
Current mobo: Asus P5G41C-M LX
Current monitor: Acer T21..(something cant remember) but 23" 1920x1080 60hz 5ms

Any thoughts? Thanks