Vista can dualboot with pretty much any other system, although compared to XP, the bootloader is very different. Using a program called EasyBCD, it's very easy to dualboot with pretty much any other system in existance (although for windows, you still need to instal it in order of oldest to newest). As for contract, I couldn't honestly care less, I bought the machine, I can load any system I want on it, having an contract that you can use Windows with Mac OS would be illegal and would be a violation of the Anti-trust agreements in US V Microsoft. As for Vista, I won't dive into that, considering I use Windows 7 which as a beta is far more usable and feels more finished than Vista ever did, I've heard that pretty much crossed the board.
@Tubster123, no, .NET Framework is a proprietary MS technology and anything like it is not avalible on any other system. Until Zune is no longer dependant on .NET Framework (which is pretty much impossible, as it's built ground up using it) and the Windows Media Player Engine, it simply will *NOT* work on Mac OS. That simple. Why this thread is still alive I don't understand.
The Zune is a good machine, so is the iPod, so is a toaster, what's your point? Zune 120.