GoddersUK wrote:
Hi, I'm a Mac.
And I'm a Surface
...

lol, maybe something more subdued.

A series of commercials each showing one task...
Transfering/Organizing photos:
The Mac -- plug in cable, transfer, click around in iPhoto.
Surface -- place camera on Surface, pics spill out, direct manipulation...
Music:
The Mac -- dock iPod, click around in iTunes
Surface -- place Zune on Surface, sync wirelessly, direct manipulation...
Scan/OCR Documents:
The Mac -- connect scanner, install software, scan documents one by one.
Surface -- place multiple sheets of paper on Surface, say "scan documents", scan completes and virtual, searchable copies appear on screen ready for annotation, correction, oh and uh ... direct manipulation

Games:
The Mac -- *crickets*

j/k
Surface -- show 4 people at a Surface playing
Halo: Gaming Evolved (zoom out to show additional Surfaces with other people playing the same game in a big Surface LAN party and on Xbox Live!

)
Of course, I doubt MS would ever do the MvPC thing. They'd just show the scenario as "the old way" using a generic Windows PC vs "the new way" with Surface.