the real question is how much money are you willing to spend.
there is no way in hell i would carry a 5.5lb laptop with me. I know that i7 and big screen is awesome, but no way. Unless someone is doing CAD or Photoshop, for most general activities, a 5.5lb laptop is overkill. The Microsoft Surface Pro is 2.5 lbs, Mac Air is 2.3
if i was going to buy only 1 thing (and i had the money), it would be a lighter laptop. 2 pounds saved instantly. In my pack, 2 pounds savings instantly is HUGE. not to mention space and bulk saved. Recently, i got so tired of lugging my 3# laptop around, i got an Ipad Mini (immedietly jailbroken) and havent looked back. Obviously, you cant go that drastic route, but to the point is, I came to the point where I had to access my needs vs. wants, and to save 2#, I was willing to honestly assess what i was really doing with my laptop and come to the realization that i could do it will a lighter product. Everyone is different, but most people really dont need a huge screen and i7.
The second big change would be sleeping bag. Do you really need a 0 degree for this trip? at 3.6 lbs? If you think you can squeak out a 20 degree bag, and money is an issue, the Kelty 20 isnt too shabby for $120 and weighs around 2 1/2 pounds. also it compressed suprisingly well. Yea, the Western Mountaineering posse will secretly mock you, but screw them.
I use a Deuter Act Trail 32. It has one of those metal bars shaped in a U for a frame. It compresses really well when not full. I am not a big proponent of bringing a separate daypack, but i am a semi gear weanie at times and so i cant justify those extra ounces. Its just not logical to me, although I can see where in certain situations it might be valuable to have. I contemplated doing that at one time, but that was when I had a big heavy pack and didnt want to lug it with me everywhere.
what i did instead was focus on upgrading my gear to decrease my bulk and weight so i could fit everything easily into a 32L pack, so I really wouldnt mind carrying it around with me to begin with.
I would highly suggest, considering you are going to be carrying a 5.5lb bulky laptop, to have some sort of frame on a backpack, however minimal. Basically, if you dont have any rigid structure or frame, your laptop will become the makeshift frame for it, and put a lot of pressure and stress on it (assuming you put it against the back). Incidently, This will quickly leave permanent marks on the screens from the keyboard being push against the screen, plus, i find it to be uncomfortable anyway.