It was only a matter of time, and the time has now come. Expect to see benchmarks within the hour or so of running games under XP using this technology, but for the time being, Apple has announced Boot Camp, technology that will be in 10.5 (Leopard) that allows dual-booting.
The big news here is two-fold: first, the introduction of Apple-provided drivers for video, backlight, etc., which is essential to a reasonably fast running system. Second, the repartitioning of the hard drive in a fashion that is both easy to do, and easy to _un_do. So, once you're doing with the windows experiment, you can put it away and regain your hard-earned disk space for a more useful purpose.