A computer's processor is the "brain" of the machine, controlling what the computer thinks and does. The processor is also often referred to as the central processing unit (CPU).

The performance of a processor is generally measured by its internal speed. The unit of measurement typically used is megahertz (one million cycles per second). So, theoretically, an 800 MHz computer processes data internally (calculates, compares, etc.) twice as fast as a 400 MHz computer. Things like disk speed and memory, however, also play a role in the computer's overall performance.

PC Processors

Most high-end business PC computers use the Pentium III processor, which comes in speeds ranging from 450 to 933 MHz (a 1.13 gigaherz version is expected Q2 '01).

Intel also has a very new processor that was launched on November 20, 2000, called the Pentium 4. It's currently available at clock speeds of 1.4 and 1.5 GHz. This processor is aimed at the extremely high-end portion of the computer market, particularly for workstations, but should eventually work its way into the mainstream.

You may also see some other variants of the Pentium available for sale. PCs based on the Pentium II are typically two or more years old, but will be fine for general office applications. There are also the Pentium Xeon and the Pentium Titanium, which are designed for servers rather than desktop PCs.

Most budget PCs - PC's priced less than $1000 - use Intel's Celeron processor. This chip ranges in speed from 500 to 733 MHz . Celeron chips are designed with less performance level than the Pentium chips so the computers that contain them are aimed more at the home and college dorm environment rather than the business environment. But a computer with a Celeron chip would also be perfectly suitable for any employee who only uses a computer for light office tasks such as scheduling and data entry.

Businesses can also choose from a number of non-Intel processors. Competing against Intel's fastest Pentium III is AMD Corp.'s Athlon processor. It is available in speeds that range from 850 MHz to 1.2 gigaherz (GHz), and has performed very well in tests against the Pentium III. AMD also has a processor called Duron - available in speeds of 800, 750, 700 MHz - that competes with the Pentium III of equivalent speeds.

AMD also makes a process called the K6-2, which is roughly equivalent to a Pentium III running at the same clock speed.

Another alternative is VIA Cyrix M2 processor and VIA Cyrix III processor from Via Technologies Inc., which compare quite favorably to the Celeron at similar clock speeds.