I’ve been saying that on the Mac, you CAN dual boot or slick/install XP because Apple has made a point of making XP drivers available for all their Intel-based hardware. And they will continue to do so.
And you're right -- our comments have been overlapping. ;-)
Your answer (get Mac hardware, wipe OS X, install XP) is the correct answer for somebody who wants a screaming machine and doesn't have requirements for hardware that only a PC would satisfy.
And as I wrote a minute ago, I've done what you propose, and it rocks. It's just an answer to a different question than I thought we started with. ;-)