Wine is a Microsoft Windows compatibility layer (or program loader)
capable of running Windows applications on i386 and compatible CPUs.
Windows programs running in Wine act as native programs would, running
without the performance or memory usage penalties of an emulator, with
a similar look and feel to other applications on your desktop.

Many applications already work, more or less, including versions of
Microsoft Office and several games.

WWW: http://www.winehq.org/