Thanks for question. Let's see, you are looking to purchase a Dell notebook with an Intel single-core processor. You're first question, what is the best choice between single-core and dual-core? Basically the difference is that the Core Duo has 2 processing cores and shares a larger cache memory as compared to a single processing core. Because the designs are significantly different, you typically can't swap from a single-core processor to a dual-core on the original single-core motherboard. This is due to differences in the chip set that supports the processor. Let us know if this helps answer your questions.