I belong to that freakish 1% who need to run VMs, Visual Studio and some heavy-duty software so I may be biased but the PC is not over because current tablets and smartphones are great at consuming stuff, not creating. To create you still need a PC.
Yes, for the average user the definition of PC has changed and Windows 8 is an embodiment of that change. So don’t say that the PC is over; say PC has evolved!