After unveiling of the first Mobile Clinical Assistant prototype, we sat down with Motion Computing CEO Scott Eckert to discuss trends in the enterprise-class tablet PC market which includes 2 form-factors: the convertibles (with an integrated keyboard) and the slate tablets. Motion Computing only plays in the latter and according to Eckert citing IDC, the slate market opportunity is about 50,000-60,000 units per quarter with a projection in excess of 40% growth over the next 5 years. The company focuses on three vertical markets: healthcare, field sales automation and state/local governments.
Eckert also explained why Motion Computing tablets uses only Windows,

We standardise on Windows XP and Vista because the features of the tablet are very will developed in the Microsoft operating system, particularly Vista with dramatically improved hand-writing recognition and pen navigation through the OS shell [...] so the OS is very good for tablets and that's not true of any of the other OS in the market

and Intel chips,

For the mobility products, Intel has a compelling product roadmap with high performance, low battery life and a good wireless platform