Bochs (AKA BOX)
Project Source code pages
Mac OS X packages built by Chris Roberts
This application comes in two flavors:
DMGOS X 10.2 Tested Version 2.02-Carbon Does Not require XWindows OS X 10.2.x only.
PKG: Version: v1.4-Carbon Does Not require XWindows
XPM: Version: v1.4-Carbon Does Not require XWindows
SOURCE PKG: Version: v1.4-Carbon Source
SOURCE XPM: Version: v1.4-Carbon Source
Version: v1.3X Xwindows Version and Disk Images
HTML documentation

The Xwindows Package Requires the Xfree86 and XDarwin packages to work!
Get the Combined package from the Xfree86 page here
The Xwindows Package also requires The DLcompat Lib

Bochs is a highly portable open source IA-32 (x86) PC emulator written in C++, that runs on most popular platforms. It includes emulation of the Intel x86 CPU, common I/O devices, and a custom BIOS. Currently, bochs can be compiled to emulate a 386, 486 or Pentium CPU. Bochs is capable of running most Operating Systems inside the emulation including Linux, Windows® 95, DOS, and recently Windows® NT 4. Bochs was written by Kevin Lawton.

Bochs can be compiled and used in a variety of modes, some which are still in development. The 'typical' use of bochs is to provide complete x86 PC emulation, including the x86 processor, hardware devices, and memory. This allows you to run OS's and software within the emulator on your workstation, much like you have a machine inside of a machine. For instance, let's say your workstation is a Unix/X11 workstation, but you want to run Win'95 applications. Bochs will allow you to run Win 95 and associated software on your Unix/X11 workstation, displaying a window on your workstation, simulating a monitor on a PC.