the majority of emulators you'd want to use on a mac have been ported from windows by richard bannister
there's a concise list of emulators that he's ported there.
the only thing is.
they're hardly usable until you pay him $25 for his "emulator enhancer"
whats the emulator enhancer you ask?
Its all the features you'd expect on a console or arcade emulator, like pad support, video filters and a full screen mode.
so I really wouldn't bother if I was you, there are some emulators that have got pretty decent osX ports released, though the only one that comes to mind is snes9x.
if you actually want to emulate a vaguely modern machine like a psx or a saturn, stick with xp. bootcamp works fine for me.
if I haven't made it clear enough, richard bannister wants you to pay for his otherwise crippled software that other people have written and he has ported. if you give him any money you are fucking insane.
i have a myspace because I am actually a 12 year old girl from wisconsin