The word 'Dual Core' simply means that there are 2 unit processors in one chipset, resulting in higher multitasking ability with less power consumption.
If Celeron processors are for basic user, Pentium processors are for intermediate users with more advanced computing needs such as video editing, video rendering, mathematical modeling (CAD, graphics design, rapid prototyping), 3D animation design, heavy graphics games etc. Intel keeps developing Celeron for its entry level - low cost segment, as a proof, Intel will soon release Celeron Dual Core processor. Due to its limited performance, the price of Celeron processor is much cheaper than the other families, however it doesn't mean that it's outdated. The letter 'M' and 'D' denotes that it was specifically designed for Mobile (laptop) and Desktop computer. This processor is basically designed to serve basic computing needs such as, writing documents using a word processor, making spreadsheet or presentation, browsing Internet, chatting, blogging, light games etc. Intel Core : Core Solo, Core 2 Solo, Core Duo, Core 2 Duo, Core 2 Duo Extreme
