All processors have a core. A processor also contains some memory, often referred to as cache, either L1, L2 or L3, depending on how close it is to the core, and the core itself, as well as a few other essentials. The core is the "brain" part, it performs all the big calculations that are needed for the various things a computer does.

Computer cores have been increasing in speed, and increasingly quickly. Manufacturers were in a race to have the chip with the fastest speed, measured in GHz. One surprise is that despite these increases in clock speed, the actual speed of programs didn't increase proportionately.

As modern programs make much heavier use of other computer parts like memory, and there are often many running at the same time, another approach was needed.

Dual core processors were the answer.

By putting two "brain" parts into the processor, you can run two programs on two cores, without having to share it between them. The effect of this is that when running two or more programs, the processor can now handle much more as a whole.

The part about them that might disappoint is gaming.

Unlike the multitasking environment that is usual for a computer either at home or at the office, games rely on the brute force of a powerful processor to help them along. So far there is no technology to take advantage of the two processors, like the ability to split its tasks over two cores. Most gaming has not improved with this new technology.

As with processors in the past the mainstream of dual core processors is dominated by the two big guys, Intel and AMD.

Intel offers two processors in its range, same processor, just different speeds. The lower priced of the Pentium D processors comes in at around $250. This price is reasonable considering how much you would pay for the top of the line single core processor.

The Pentium D is based on the same core as it's single core counterparts, just two of them inside. Its boost in performance is quite notable, and makes it presence felt in the multitasking environment.

The AMD Athlon X2 is AMD's offering in the dual core market. Unlike the Pentium D its lowest priced model comes in at a staggering $400. It's not expensive compared to processors like its FX series, which are over $1000, but in comparison to Intel it's expensive.

It too is based on the same core as its single core cousins and also offers the same performance increases.

The price of the AMD is surprising. From a company that became renowned for it's low cost, high performance processors this is quite a blow. Even the upper model of the Pentium Ds comes in at less that AMD's cheapest model.

The price might be justified if the AMD actually gave a significant performance boost, but it doesn't.

For the first time in a long time, I think I would be willing to switch back to an Intel processor. Although my preference is not for dual core, if I had or needed to switch I would certainly go straight for the Pentium D.

And finally, how do they compare to their now out of date traditional processors?

Considering how powerful processors have become I would still not make the switch. Dual core has not been around long enough to produce low cost, slightly out of date models. The power of the AMD Athlon 64 3000+ more than does it for my computing needs, and that's where I would stay for now.

So for those who are looking for the next cool thing for their desktop computer and price is not a huge issue, this would be your best choice, but go for the lower end Pentium D.