There have been reports in the internet of people installing both OS X (probably hacks of versions 10.4.1 & 10.4.3 for Intel) and Windows XP on a Intel PC. OSX is a unix based OS, just like Linux.

An alternative to booting Unix/Windows via a bootloader is running a piece of software (like www.vmware.com ) that allows you to run BOTH OS(s) simultaneously (one of the operating systems is the host, the other is the guest). For this you need a considerable amount of RAM.

-- José.