Right now Lenovo has a 25% off coupon + 8% cashback, but it ends on the 17th. I am having a really hard time choosing between the T420 and the T420s. I will be going to university for mechancial engineering, so my main concerns are portabilty (which the T420s has), battery life (which the T420 has), and graphics power for AutoCAD (which both can have with the NVS 4200M). It seems the main difference between the two laptops is that the T420s comes with an Intel Core i7-2620M processor instead of a i5-2540M, and it is about a pound lighter. The T420 is roughly $200 cheaper, so I would use this to buy an SSD. My question is, is the T420 that heavy? If you put it in a backpack with a couple textbooks, would you actually benefit from the T420s' lower weight? This seems to be the decision maker. If weight does not seem like an issue, I will go with the T420.