Yes if your TV rated for 3D or no if it simply say 120hz.
I won't go into details but there are so called "120hz" TVs out there that can't actually do 3D. They take 60hz signals and add an extra frame inbetween to give slightly more fluid motion. They can't really do 120hz.
120Hz HDTVs work differently than 120Hz PC monitors.
To put it simply, 120Hz HDTV creates extra frames to make videos look smooth and also give that "live-ish look" like a news program or soap opera. Creating these extra frames takes time and increases input lag; the time it takes between you making a move or firing a gun and when it is displayed on the screen.
For gaming on a HDTV you always want it in 60Hz mode.