> From a compatibility point of view, Windows rules supreme. I don't know any desktop OS with this kind of application compatibility.
BeOS/Haiku? Don't drivers for BeOS still work on Haiku today? Now if you meant "used desktop OS", then I do think I'd have to agree. Though, pre-NT-era apps (particularly games) can no longer work (I have a few laying around), WINE-on-Windows might end up being the best way forward for that compatibility.