Is it my imagination that OS/2 did essentially the same as far as the unified appearance with windows 3.x in the Warp days? And didn't NT used to run Windows on Windows in a seemless view as well in an essentially virtualized environment? Though I understand the virtulization discussed here is a somewhat different concept as they weren't emulating hardware, but werent they essentially virtual machines? And now that OSX is running on Intel type hardware is this level of emulation necessary any longer? (I can think of circumstances where the answer to that would be yes, or no).