I honestly think that is the big downfall of Windows. We haven't seen how Windows 8 will run on a tablet yet, but I don't see it being lightweight enough in terms of memory, CPU and power to run on current tablet technology.
I can't believe that MS are still trying to shoehorn the full version of Windows onto tablets, they should have a cut-down version and a full version or disaster awaits. It seems to me that the way they are going they will have people running Windows 8 on laptops/desktops/VDI who will never use the Metro UI (why would you want to?), and people trying to run Metro on tablets/phones who won't be able to because hardware constraints mean the base OS will be slow. Both sets of users will be failed.
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