I've always seen a PC as being a computer descended from the IBM device in 1981, based on x86. My definition would include any such device running DOS/Windows/Linux etc and indeed all Macs since...
Dell XPS 10 is now only £199+VAT in the UK.
That's not good news for Surface RT here.
It would be useful to know as a comparison how many desktop applications people are launching in a day.
Without knowing that it's very hard to put these figures in context.