Even if Apple did ship an Intel based box you will never see a version of OS X that runs on a system not made by Apple. Apple is a hardware company, that is where their profit is. By controlling the hardware platform they are able to ensure a higher quality user experience, by developing and QAing on a limited range of hardware.

Most user problems with XP or Win2K come not from the software but from the vast array of different hardware people run on. It's just not possible to do extensive QA on all combinations of PC hardware available.