Thank you all for your replies, now I have a better idea of what I'll need to reach 120fps (or at least to get close to that framerate).
To answer a question in the first page of the thread, "Why would I want 120fps?", it's mainly because of this:
http://www.blurbusters.com/zero-motion-blur/video/
Strobing the backlights of a 120hz (or faster) 3D LCD screen, the movement becomes as fluid as on you could see on a CRT screen.
Quoting a description from their website on how strobing works:
The backlight is turned off while waiting for pixel transitions (unseen by human eyes), and the backlight is strobed only on fully-refreshed LCD frames (seen by human eyes). The strobes can be shorter than pixel transitions, breaking the pixel transition speed barrier! In addition, it eliminates the sample-and-hold effect.