Forget the backpack. Better yet, get a computer bag on wheels. I used to carry a shoulder computer bag, then a backpack-and got tired of lugging stuff on my shoulders. My bags kept getting stuffed with more and more stuff-to the point where it wasn't feasible to carry it around.
My wheeled computer bag can hold more stuff (currently weighs around 42lbs) and I can get around the airport faster, and look more professional when I arrive at an appointment than with a backpack. My laptop is in a separate, neoprene case in my bag-so when I just want to travel light, I can.
Originally Posted by Efrem
Instead of changing your laptop, you might consider changing what you carry it in. I go all over the world with a "desktop replacement" laptop with a 17" screen, plus all the usual other stuff and lots of etcetera depending on where I am and what I'll be doing. I have no problems with this load because I put it in a serious backpack with a waist belt and a sternum strap (the same one I use for long day hikes). If I had a typical "book bag," let alone something with a single shoulder strap or just handles, I'd feel differently about adding a 6+ pound computer to the mix.
(Of course, the places you go have to be backpack-friendly. It wouldn't fit into every business environment. And you have to be personally OK with the approach.)