Those other intros are too hard to play.  This is the
CORRECT way to play the intro riff:

-----------------------------------------------------
-----------------------------------------------------
-----------------------------------------------------
-----------------------------------------------------
---5---5--7-77-7-77-7--------------------------------
-7---7----0-00-0-00-0--------------------------------
Clean-----Palm Mute.

Play that over and over.  In main vocal part, do a fall
during the muted part.