Having experienced back pain recently I decided it was time to bid farewell to my over the shoulder laptop case and buy a traditional rucksack design. It was important to me that it not be a large rucksack as I have a tendency to pack these to capacity which I believe would leave my back in a worse condition than it already is. Also, from an aesthetics point of view, smaller is better in this case. I love the colours of the bag and it's compact design. It has a degree of water resistance and a handy little cut-out to put earphones through for an MP3 player and such. There are many pockets and even a handy little case for the power adaptor of your laptop.
I own two laptops, a rather bulky 17inch Dell Inspiron 6400 and a somewhat sleeker 13inch Macbook. I have fitted both of these in the bag with ease (although not both in the designated slot for the computer at the same time). The shoulder straps are comfortable even with a reasonably heavy load but thankfully, the option to stuff endless amounts of gubbings within is not there due to the sensible size. The handle on the top of the bag is extremely useful also as well as a whole array of pockets and slots within the bag itself.