I remember seeing an article in Maximum PC where some dude had every version of Windows (v1, v2, v3, WFWG, 95, 98, ME, NT, 2K, XP) running simultaneously on one computer in separate VM sessions which leads to the question - why?

I'm not seeing the practical side of running Vista on a Mac OS Intel box other than for the novelty unless there is a need to run some type of proprietary Windows software, i.e. a specialized work or business program, but what's the point when PC's are reasonably cheap?