Free PC / Intel i86 Emulators, Virtualizers and Virtual Machines

Intel x86 emulators imitate an Intel x86 (or AMD) machine (such as a Pentium or Athlon) on platforms that may or may not have an Intel/AMD processor. Using such an emulator, you can install and run i86-based operating systems like Windows even on systems like the Macintosh. Even if you are already using a machine with an Intel or AMD chip, they can be useful in allowing you to run two different operating systems simultaneously (eg to test software, etc). Since such software have to emulate all the processor's instructions, they can be excrutiatingly slow. If you are already using an x86 machine, you might want to choose a virtualizer or virtual machine instead, which only virtualizes hardware other than the CPU. This page also lists free virtualization software.

Note that this page does not list commercial PC emulators and virtualization software. If you need a commercial solution for their support, completeness of implementation, speed, etc, you might want to take a look at Parallels Desktop for Mac and Parallels Workstation, which allows you to run Windows (and other PC operating systems) on an Intel Mac OS X.