The Aer Fit Pack and the Thinkpad 13 is a perfect combination. The laptop is relatively light, coming at 13 inches and fits snugly into the laptop compartment of my Aer Fit Pack. I brought my laptop to work to see how the bag would feel on my back when I carry my laptop with me, and with the added weight, it still feels comfortable using the bag. I have yet to fully load up the bag with my running shoes and running clothes, towels, water bottle and shower foam. I would be a little bulky in the end, but I doubt all those extras would significant add to the overall weight that I would be carrying to school. Afterall, my new New Balance shoes are pretty light, and all I would be bringing next is a pair of running shorts, and dri-fit t-shirt for running with a small tower and a small bottle of shower foam to shower after a run.
All in all, I am almost ready to start school in January.