The next most important component to building a Photoshop computer is the processor, also known as the CPU. The processor processes all the calculations and instructions required to run tasks such as a filter. Many Photoshop filters are processor intensive and their speed depends on the CPU.
As new and faster processors emerge, software will adapt to take advantage of the faster processor speeds. The fastest processor usually cost around two to three times more than the average processor and slower processors aren't that much cheaper. When choosing a processor, choose one that's the best bang for the buck or one that fits within your budget.
If you'll be using more than 2 GB of RAM, you should be using a 64-bit processor. Adobe Photoshop will only be able to recognize up to 3.5 GB of RAM on a 64-bit computer. The current generation of processors is all 64-bit and there's little reason to stay with 32-bit processors. Although most applications are 32-bit, support for 64-bit is growing and new 64-bit computers will be able to take advantage of the larger 64-bit address space. Only Photoshop CS2 and future versions of Photoshop support 64-bit.
Some recommended desktop 64-bit processors are:
Most new processors are dual core meaning that there are two processors in one chip. This allows improvements in multitasking. Photoshop 4.0 and above supports dual processor configuration and will benefit from a dual-core processor.
{mostip}Update: Quad core processors are now available and benchmarks show that Photoshop does support quad core processors and benefit from them. Currently, quad-core processors are expensive so we don't recommend getting them unless everything else in your computer is the top of the line. While they may perform faster in Photoshop, keep in mind that not all software support quad core processors and those software will not use all four processors.{/mostip}
{mosimage} All current generation of Macs use Intel processors. For users building a Windows computer, you have the expanded choices of both AMD and Intel processors. Currently, we recommend using an Intel Core 2 Duo processor over the AMD processor. Intel Core 2 Duo processors provide more bang for buck compared to AMD processors. For example, the Intel Core 2 Duo E6600 is cheaper and faster than the AMD FX-62. However, if you're looking to build a budget computer, nothing beats the price of a low end AMD Sempron CPU.