Dosbox is a full x86 emulator written in C/C++ with sound and dos. It's main use is to run old dosgames on platforms which don't have dos (win2K/XP/FreeBSD/linux). The most important new features: basic Protected Mode support, basic VESA, DPMI and lots of bugfixes.
Get it at:http://www.sourceforge.net/projects/dosbox
includes a list of working games. Feel free to add your own games to it.