Intro (Main Riff)
e|-----------------------------------| 
B|-----------------------------------|
G|-3-3xx-5-5xx-10-10xx---------------|   
D|-3-3xx-5-5xx-10-10xx-8-8xx---------|
A|-5-5xx-3-3xx-8--8-xx-8-8xx---------|
E|---------------------6-6xx---------|

Thats most of the song, Some parts just alternate strumming patterns and tempo.
Listen to the song and you'll understand it.
http://www.youtube.com/watch?v=g1ValsnM4K8