The power brick only weights about 2-4 pounds i say but yes the battery life sucks with them. You can only go 2 hours with power saver and the ALienwar fx off.
Alienware laptops are pretty bad Ive had countless problems with mine and they still won't send me a new one even though i have the warranty for it. You can make/customize a laptop from a no name company for cheaper and it will last the same amount of time. You are buying an Alienware for the looking and brand instead of the customer service and quality they used to provide before Dell bought them out. Wish i would have never bought it.
Owner of a M15x Alienware laptop.