Cases and bags to transport your laptop vary in size, shape and types of material. Buy one that you accommodates all of your laptop accessories. The more external devices you need, the larger your case will need to be and the more it will weigh. The more durable and robust your case, the better protection your laptop will have but, again, the heavier it will be. Most laptops purchased through major suppliers come with a soft case that doesn't offer much in the way of protection so it may be advisable to shop around for the most suitable design.