Correction: Mac's new OS does NOT work on PC's...but Windoze OSes do work on some Macs. I think the writer got it backwards.
And only a foolish Mac user puts Vista on their machine! Well, ok, only a fool of either stripe puts Vista on anything but their "to avoid" list!
Macs and Windows PCs run on the same hardware, and the stuff that used to be in ROM is now in software. Mac OS can run on any generic PC, but it takes a hack and you have no support. If your sound card, video card, parallel-port printer, and so on do not have Mac support, you're out in the cold.
I agree in general, but I have XP on my Mac via Parallels. I don't sweat viruses or spyware much; Windows is in its own little sandbox, and if it goes Tango uniform I can wipe and restore. I don't keep any meaningful data in the sandbox.
Some day, I might consider running Vista. But not outside the sandbox.
Correction of YOUR Correction: Mac OSX does run on MOST PCs. There are dozens of websites which tell you exactly how to do it and where to get any help doing it.
Google OSX86