Pretty much.
The 120Hz technology is great for fast paced games as it makes everything very smooth and responsive - very much like playing on a good CRT.
However, if you want to watch films/TV then you really want to get a monitor (or TV) with a VA (or possibly IPS) panel. Panels like these have much deeper blacks, more colours and wider viewing angles than TN panels such as the one used in the Alienware.
Here is a good article that explains the differences in these panel technologies.