Market research firm Canalys kicked off a bit of a high tech shit storm when it bucked convention by counting tablets as PCs. While most analysts have the PC industry shrinking, Canalys has it growing, thanks to gangbuster tablet sales from the likes of Apple, Samsung, Amazon and other tablet makers.

But are tablets PCs? Critics of Canalys argue that if you're going to count tablets as PCs, why not large screened smartphones? Or all smartphones for that matter? After all, the iPad and the iPhone share processors and operating systems. Where's the dividing line?

On the other hand, if tablets aren't PCs, what does that make the Microsoft Surface? Is a touchscreen device with a keyboard really all that different from an ultrabook with a touchscreen?

Personally, I'd go with screen size as the dividing line, as that's what really determines the usefulness of a device for light PC work. Add a keyboard or keyboard case to any tablet and it's as useful for the bulk of traditional PC tasks as any netbook. And netbooks were always counted as PCs.

But maybe I'm an idiot. What do you think?