Which one of these video cards do you think is the best?
By that, I mean best "Bang for your buck"
GTX 560
GTX 550ti
Well, to be honest, if you are doing a $700 build, you should be aiming for more than a 560.
Even a $500 build can achieve a HD6870, which is marginally better than a 560.
For $700, I'd expect an i5-2500k CPU and at least a HD6950, which is comfortably better than even a 560Ti.
What about a laptop for $400 or lower will it be able to run good games(LAPTOP).
Not really. You'd want to spend more than that if you wanted to game properly on it. Sure, it would run games, but very laggy and not very enjoyable.
If $400 is your absolute maximum budget then I'll pick you out the best one for that price if you wish.
EDIT: Broke my 11111th post to post this D: