A dual-core processor is much faster than a single-core processor since it is two processors mounted on the same die. Each of the two processors are the exact same, one mounted on the top, and the other mounted on the bottom of the die. Since there are two processors, there is the ability to perform twice as many computations in any given amount of time, making it quite clear why dual-core proceesors are faster than single-core processors. With two processors sharing the workload, the upload and download times are much faster, and three dimensional manipulation becomes more accessible without over-clocking the CPU and freezing your computer. Dual-core processors will make the graphics of your high definition LCD monitor a lot clearer and crisper, and the flow of multi-person role playing games a lot more fluid.
As the market stands now, the advantages of dual-core processors are limited to the people who put their computers to the limits of their capabilities. A high definition role playing, shoot-em-up game will drain the resources of a single-core processor much more than a dual-core processor, and if you want to run any other applications at the same time as playing the game, well forget it, you will most definitely over-clock your CPU and freeze your computer, forcing a re-boot with the single-core processor. But, how did we survive without the dual-core processor for so long? The Sun Microsystems have had astounding computational powers for years, but the price is as astounding as the power. Basically, you get what you pay for.
As the processing power of computers is increased pretty much every six months, the software applications, games and accessories are striving to upgrade their software to take full advantage of the increased processing power provided by having two processors running full time, as opposed to one, which is what we have had up until a couple of years ago. Games that are now on the market will most likely soon have 64-bit, as well as dual-core processor designated games, meaning they would use the full powers of the dual-core processors and provide better detail and more available actions and processes. But the need must be present for the power to be used.
For multi-player gamers, 3D gamers and people who use engineering drawings involving 3D CAD (computer automated design, or computer assisted design), students relying on research for major theses, like in the biology, law or medicine fields would benefit from a dual-core processor. The average person who uses a word processor, maybe email and chatting online, doing their bill payments and online banking through the internet, and uploading pictures and video from digital cameras to morph and make printouts may not see the benefits, other than the better display capabilities for high-definition LCD monitors, and for using external displays, like high-definition LCD or Plasma television sets.
So, if you already have a computer that has a single-core processor, upgrading to a dual-core processor would be more expensive than the benefits would justify. You would need to buy a new motherboard that allows for a dual-core processor, and probably a graphics card that uses the dual-core processor as well.