Hey, sorry to say, not real likely
While it'd be a great show for Apple (almost forgot to capitolize

), I can't think of a single pc maker out there who'd willingly embarass themselves like that. Sure, Compaq's been doing it for years, but not quite this blatently
The only other option would be for Apple to make their own PC to put on display, but as soon as word got out Apple had made their display pc, the message would be lost.
Sorry, nifty idea, but you'd need a really naive pc maker, and Apple'd probably pick up a lawsuit in the process (slander or something....)