There's another technical issue: as you probably know, Apple is using EFI, not a traditional BIOS, and we don't know how that will affect the ability to run OS X off of a Mac.
Also, the likelihood of OS X running the way you'd expect is fairly slim. For example, you may not have any video drivers, so you won't get Quartz Extreme acceleration - some CoreImage apps may not even run at all. We don't know if there will be necessary drivers included for network adapters, sound, and so on.
In short... wait for Windows Vista to be released, and buy a Mac that meets your requirements.

You'll probably have a much better time of things!