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, Pentium, Pentium Pro or AMD64 CPU,
including optional MMX, SSE, SSE2 and 3DNow instructions.

Bochs is capable of running most Operating Systems inside the emulation
including Linux, DOS, Windows® 95/98 and Windows® NT/2000/XP.

Bochs was written by Kevin Lawton and is currently maintained by the Bochs
project.

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. 

WWW: http://bochs.sourceforge.net/