Emulators
Have you ever used VMware? There is also GPL project like VMware called Bochs IA-32 Emulator. It is an x86 PC emulator. it can be compiled to emulate a 386/486/Pentium CPU. It runs on Linux, Win95, DOS and WinNT4.0.
Well, these are not the only x86 emulators available. There are a lot more. You may try out Plex86 or Wine or User Mode Linux or a386 or the Brown Simulator, GPL-VM or Connectix Virtual PC or probably Win4Lin.