It's not just the processing power that matters: battery life is really important to making a tablet useful.

"Up to 6 hours" (as quoted for that Binatone) won't cut it, I don't think, even though the hardware's otherwise well able to handle email and similar. Unless you're really assiduous about plugging it in all the time you're not using it, it'll be dead every time you pick it up!

Cheap tablets probably make excellent status boards, though, left plugged in and running a browser.