The funny thing is that the biggest advantage of a Windows NT tablet over an XYZ OS tablet is that you can install software you already use, and there is a vast supply of socuh software.

Yes, there is a ton of Windows software that runs on ARM: Windows CE ARM. But that won't run on Win8/ARM. Win8/ARM may turn out to be a loser: no more useful than another OS and a late-comer to the party.