Anyhow, regarding Windows compatibility, A great methods looks to beone Linux users have been using for a while called Wine. DarWine
is a port of Wine to Darwin, the underlying Unix layer of OS X. This should allow seamless running of Windows programs inside OS X on an Intel based Mac. There will likely be some speedbumps, but it is very promising.
Beyond that, Intel will be putting technology into the CPU to help enable systems to run multiple operating systems at the same time. Think of it this way. You boot your Intel based Mac, select to start OS X and Windows XP, then hit a key combo to switch between the two. Hard to say if or when this will work, but based on Intel's timetables the technology will be in every Intel CPU by the end of 2006 I believe.