http://www.youtube.com/watch?v=MK45fEgNdi8
^had to be done
I agree with most the above posts, in a 5man situation cast whatever you think will cover incoming damage, in 25mans your GCD's should be either PW:S, POM or penance, I wouldn't recommend renewing as disc as thats the holy priests/resto druids job, your there more as a health buffer than a healer.