A touchscreen that docks to a keyboard eh? Have you seen the iPad keyboard dock? Aside from lack of mouse (which would be marginally useful in iOS, if at all), that's what an iPad + keyboard dock is.

Compaq and some others made resistive tablets like you might be getting at a decade ago and one of the biggest problems was that they all ran Windows XP and were underpowered, so you just got a smaller, heavier, less capable Windows box you could draw on.