Usually the assassin's creed series is not much graphic demanding so playing it on an hd 4650 is not going to be much of a trouble on high setting it seems ...so enjoy...
you can many of the games like pop forgotten sands, bad company 2,assassin's creed 2 , dirt 2 etc on high with hd 4650 on your laptop provided you play the games on the resolution suggested by Maziar