I think the magic number for tanking with a pally is 200 spell damage. I have a little over 200 and the mobs don't come off of me. I cast sal on my shams, pull with shield, con + shield once and i don't lose agro (then again i also have iron shield spike on and a shield that does poison damage to them so that helps too)... Tanking is so easy, when i look at my tank half the time she is not even swinging her mace... lol.