HTOTM: FUSION
the size of the screen has nothing to do with your gpu btw, you can have a 19" screen with a higher resolution than a 52" screen which would take more to render. most likely the 52" screen is 1920x1080 which now days is the standard resolution for monitors and tv's over 32" and going from a 19" 1920x1080 screen to a 52" 1920x1080 screen wouldn't affect performance in any way (aside from possible ghosting on one or the other)

since standard laptop resolutions seem to be 1366x768 or 1360x768 going from that to 1920x1080 will impact performance but if you get something around the gtx460m 1gb or 1.5gb in the laptop or better you would actually benefit from playing on 1920x1080 anyway.

and yes i agree with isaac, if you dont care about the alienware look check into the Asus ROG series laptops.

cheaper and you can find ones in the 14" to 15.6" range which isn't too bad, although if you're depending on the size then the m11x would probably be the answer.
You don't say?