@Dr Herbie: Perhaps usable, but not optimized.  There are far too many OS screens/dialogs that have tightly packed miniature controls.  The default Windows display settings for 10" 1366x768 px display make tapping on something as basic as the Close button a challenge.  Frankly there is no need for a title bar, min/max buttons when working with screens of this size.  The on screen keyboard is horrid.  I have no doubt that Microsoft recognizes this and plan to address it in Windows 8 with a Metro influenced framework.

Pen is a much better story in Windows today.  Its just that you can't find a 10" Slate PC with an active digitizer for $600.  This is the premium a college student might be willing to pay over a $350 Windows netbook.  At CES Lenovo showed off the IdeaPad Slate and indicated this may hit the market later this year at a suprisingly good price point.  So there is hope, as long as they are not the only Windows PC OEM doing so and these are sold/marketed through mainstream consumer sales channels.