core duo and dual core are the same thing, you wanna go for the faster one, and what you've heard is about i7 wich is a quad-core processor out of those options this http://www.sony-mea.com/product/vpcc...vpccw16fg_b+e1 is the best, it has more RAM, better processor, windows 7 (vista sux) and has a little geForce, that's better than the other's graphic accelerator