HERE's a photo showing the default photoshop keyboard shortcuts.
Also, having a better PC allows you to create larger designs (full HD, quad full HD, etc..)
I personally have a small Wacom tablet (the left in the picture above) and I can say it's good enough for me.
You can buy one for around 150$.
First of all, if you're using Photoshop or Illustrator you'll have many windows & panels opened, so that there will remain only a small part of the artboard visible.
Another problem if you're a webdesigner is that if you have a small monitor you can't see how your website or application will look on larger screens.
Also, having 2 or more monitors is also helpful. For example you can open Photoshop on one monitor and Illustrator on the other.
You can buy a 24" monitor for 250$ - 300$.
What makes (or made you) work faster in Photoshop? (excluding a tight deadline :) )