What version of MacOS are you looking to run? The main options for Windows are:
**Mini vMac - emulates a Plus, so small screen area and black and white only, runs up to OS 7.5.5 and 68k software. Very fast and stable.
**Basilisk II - 68k emulator, so up to OS 8.1 and 68k software only - very fast and stable.
**SheepShaver - PowerPC Classic emulator, can only run up to OS 9.0.4 (not 9.1 or 9.2) - pretty fast and fairly stable (in my experience), crashes occasionally.
**PearPC - PowerPC OS X emulator, can run OS 10.1 to 10.4 - useably fast on a fast PC, not especially stable (seems to depend a lot on which particular build you use though).
**VMware - x86 virtualiser - can run the hacked x86 versions of OS X, as long as your CPU supports SSE2 or greater.
_________________
Main system: custom C2D 2.66GHz tower/4GB RAM/2600XT 512 MB/500GB HD/XP Pro x86+Vista Business x64
Main Mac: Beige G3 minitower (Sonnet G4 500MHz/640 MB DVD/USB/Radeon 32 MB/OS 9.2.2+10.4.11)
**Mini vMac - emulates a Plus, so small screen area and black and white only, runs up to OS 7.5.5 and 68k software. Very fast and stable.
**Basilisk II - 68k emulator, so up to OS 8.1 and 68k software only - very fast and stable.
**SheepShaver - PowerPC Classic emulator, can only run up to OS 9.0.4 (not 9.1 or 9.2) - pretty fast and fairly stable (in my experience), crashes occasionally.
**PearPC - PowerPC OS X emulator, can run OS 10.1 to 10.4 - useably fast on a fast PC, not especially stable (seems to depend a lot on which particular build you use though).
**VMware - x86 virtualiser - can run the hacked x86 versions of OS X, as long as your CPU supports SSE2 or greater.
_________________
Main system: custom C2D 2.66GHz tower/4GB RAM/2600XT 512 MB/500GB HD/XP Pro x86+Vista Business x64
Main Mac: Beige G3 minitower (Sonnet G4 500MHz/640 MB DVD/USB/Radeon 32 MB/OS 9.2.2+10.4.11)