Me, I'm into power tools when it comes to removing crank arms. The easiest way of removing a crank are is use a small air hammer with a fairly blunt end attachment. You can buy this tool at your local Home Depot for less than $20 and hook it up to your compressor if you have one. Next after you have the air hammer, remove the crank bolt, place the blunt attachment on the back side of the crank arm or spider and pull the trigger one time. Your done, crank will pop off with little or no damage.
So much for Bike Shop 101, this is a proven method, so good luck.
John Alden
North Rim Adventure Sports
Chico, CA