I can already hear the IT department drooling over the prospect of a locked down machine that's cheap but still has the Office Suite and IE (the browser or large business) which frankly covers what 95% of office workers actually need.
It's a response to BYOD iPad's in the Office, not iPad's at home. Its also why I think Steven Sinofsky had to go. He wanted Microsoft divisions to fight each other, not work together.
Think of it this way, assuming Microsoft works on close integration between its products (without Sinofsky this might fly) it is in a unique position. They can offer the most complete end to end business solution for large companies. Hardware (Surface RT and x86), Phones (Windows Phone), Desktop OS, Server OS, Programming Languages, BI suites, Email (exchange), Database etc.....
I can't think of any other company that comes close to offering this except possibly Oracle and they are still missing a few things (Maybe they should offer to buy RIM?).
Micrsoft, who has approached our company to build a Surface Pro app to compete in the enterprise space.