Many of the questions from listeners and clients we field have to do with the benefits of dual core processors. It's a question on a lot of people's minds, of late. There is a lot of confusion, in part due to the large number of opinions floating about being given as fact.
This short article at hardwareinreview.com will go a long ways toward clarifying things for you. It is not overly technical, though a certain amount of detail is inevitable when addressing a subject such as this. I think you'll find it informative and not at all painful to digest.
[ See also this ACM article on desktop dual-core performance. Pete]