Hi - my first tab so go easy on me.  Pretty easy song to play.  Just listen to it 
to get the rhythm.

Standard Tuning

Intro

E||----------------------------------------------------------------------||
B||----------------------------------------------------------------------||
G||----------------------------------------------------------------------||
D||----------------------------------5---5-5-5-5-5-5-5-5-5-5-5-5-5-5-5-5-||
A||----------------------------------5---5-5-5-5-5-5-5-5-5-5-5-5-5-5-5-5-||
E||-6-8-8-6-10-8-6-8-4-6-6-4-8-6-4-6-3---3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-3-||

Main riff

E||---------------------------------|---------------------------------||
B||---------------------------------|---------------------------------||
G||-0-0-3-0-3-0-3-0-0-0-3-0-3-0-3-3-|-0-3-0-3-0-3-0-0-0-3-0-3-0-3-3---|| 
D||-0-0-3-0-3-0-3-0-0-0-3-0-3-0-3-3-|-0-3-0-3-0-3-0-0-0-3-0-3-0-3-3---||
A||---------------------------------|---------------------------------||
E||---------------------------------|---------------------------------||

Chorus

E||---------------------------------|---------------------------------||
B||---------------------------------|---------------------------------||
G||-7-7-7-7-7-7-7-7-7-7-7-7-7-7-7-7-|-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-||
D||-7-7-7-7-7-7-7-7-7-7-7-7-7-7-7-7-|-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-||
A||-5-5-5-5-5-5-5-5-5-5-5-5-5-5-5-5-|-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-4-||
E||---------------------------------|---------------------------------||

E||---------------------------------|---------------------------------||
B||---------------------------------|---------------------------------||
G||---------------------------------|---------------------------------||
D||-3-5-5-5-5-5-5-5-5-5-3---3-------|-3-5-5-5-5-5-5-5-5-5-3---3-------||
A||-----------------------5---5-3-5-|-----------------------5---5-3-5-||
E||---------------------------------|---------------------------------||

Once more unto the breach!...

E||----------------------------------------------------------------------||
B||----------------------------------------------------------------------||
G||----------------------------------------------------------------------||
D||----------------------------------5-----------------------------------||
A||----------------------------------5-----------------------------------||
E||-6-8-8-6-10-8-6-8-4-6-6-4-8-6-4-6-3-----------------------------------||

That's it really, done from memory, any corrections please let me know.