As well as emulating the machines themselves, various add-on interfaces are supported, including hi-res graphics, custom character sets, sound and colour cards. As I told a relative when he started running Tiger on his G4: 'There's next to no sunlight between the two. EightyOne is an emulator for the range of home computers made by Sinclair Research (and their clones) in the 1980s.
And in terms of just out-of-the-box networking between Macs & PCs, the vanilla user version of Tiger practically eliminated any coughs, chokes and hangups between Apple's SMB protocol and Microsoft's. I have done a little with Apple's X11 distribution - of which on this Forum you'll find scads of discussion and info - in OS X, and I agree it does make up the difference between the two ( or is it three now ? ) platforms. Virtual machine imaging Mac OS X has its own legal issues: the only 'Ten Version' as I like to phrase it where Apple's lawyers would be inclined to look the other way if someone virtualised it is (drum roll please) OS X 10.4 Tiger server.
Those that exist for the direction you're choosing, even the commercial ones, have their own issues and are generally considered not worth the time money or effort. Operating system emulators tend to favor going the other way - Mac to Windows. As a long time Mac user (work and home, classic and OS X), I agree with pludi.
