A core 2 duo is a dual core processor. The difference between the core 2 series and the latest core i series is the architecture, i.e. the core i series has the newest architecture and is made using the latest fabrication techniques. So, if you're looking for a new computer, I'd at least go with an i3. The i3's are dual cores, while some of the i5's are dual cores, while the others are quad cores.