Most new computers sold are in the 2 to 3 gigahertz (2,000 to 3,000 Mhz) range. The two leading manufacturers are AMD and Intel. Usually a AMD CPU of the same MHz rating is faster than the equivalent Intel CPU because it gets more done per clock cycle. AMD uses model numbers to account for this. E.g. the Athlon 1600+ is roughly equivalent to a Pentium IV 1.6 gigahertz CPU, though it runs at only a 1.4 gigahertz clock speed. They roughly approximate the power of the equivalent Intel CPU. On the other hand, some software is tuned for Intel and may not work as fast on AMD or may not work at all. This is less of a problem than it was in past. Clock speed is misleading. A CPU with double the clock speed may run only marginally faster, because it spends most of its time waiting for RAM which is no faster. A dual CPU may run only marginally faster than a single one because the two CPUs have to keep waiting for each other for common hunks of RAM.

Intel’s value line is called Celeron. AMD’s value line is called Duron.

Intel’s premium line is called Xeon, and AMD’s premium line is called Athlon.

Intel’s 64 bit server line is called Itanium. AMD’s 64-bit server line is called Opteron.