I travel frequently with laptop. I always carry on. However, pain in neck. You will be required to take out the laptop and put in a separate bin. Same with pager, cellphone, dvd player etc.. Then rest in another bin as shoe, bag (keep cord inside bag), etc...
They always ask me to take out my laptop. I dont like it but its their rules. Chicago, Milwaukee, Minneapolis, Tampa, Columbus, St. Louis, Atlanta, Regan Airport (DCA), BWI and IAD Dulles have asked me to do the same. So expect to unload the laptop, they will take care of your laptop.