OSX86. I've installed it before, just for kicks. Reformatted that partition for more useful things, like Windows 7 but XP is my default boot.
Actually apple developers who need powerful hardware do so on boxes that are more akin to a pc in the sense that they usually come from a windows machine with a few hardware differences for the right driver support. Now that apple is all intel processors its pretty easy to do with most boxes but be careful and research a laptop well before you try because the parts are a bigger pain in the ass as far as compatibility. Its just not legal for the everyday person to do that to their pc as in the licensing agreement or whatever to osx it says you can only put it on apple hardware, unless you are a developer. doh thanks apple