I'm only just migrating users to Windows 7. Slowly. Still XP Pro for the most part.

Server 2008 R2 though, running behind that.

In some ways, depending exactly how customisable it is, the new UI paradigm could work quite well in a business context. Depends on the business... and users. The "idiot-proofing" can be quite desireable here.

On a personal basis, I like how both OS X and Windows are currently laid out and wouldn't be in a hurry to adopt anything radically different... and, yes, just want a tablet, mouse and keyboard... not a touch screen (or gesture recognition either). A Space Navigator would be nice.

By the way, it's already possible to replace the default Windows shell (Windows Explorer with Start menu, desktop etc) if you really want to, in fact:

http://en.wikipedia.org/wiki/List_of_alternative_shells_for_Windows