I know my response to Boot Camp, which allows Windows, Linux etc to be installed and dual boot on any Intel based Apple computer, is slow.
Boot Camp will definitely boost Apple hardware sales. Those who love apple, i.e. apple fans, will still buy Mac and use OS X on them. Those love Mac hardware but prefer Windows are those people who will help apple sell more hardware.
So what’s next? As Vista is delayed, Apple is likely to allow OS X to be available on any PC once their hardware sales go up a lot. Well, maybe not any PC, but Apple is more likely to license its OS X to some limited hardware producer. This way, Apple can withdraw once this is bad for its hardware sales. It depends on, how much Apple can earn from hardware compared to selling OS X.