This is the main riff.. two guitars play at the same time and they sound the same, just 
different notes.

Guitar I:

e|-----------------------------------------------------------------|
B|-----------------------------------------------------------------|
G|-----------------------------------------------------------------|
D|-------9-7----7--------------------9-7------7--------------------|
A|-7-7-------10---10-9-10-9------7-7------10-----10-9--------------|
E|---------------------------10-----------------------10~~~--------|

e|-----------------------------------------------------------------|
B|-----------------------------------------------------------------|
G|-----------------------------------------------------------------|
D|-------9-7----7--------------------------------------------------|
A|-7-7-------10---10-9-10-9---------3~-5~-7~-9~--------------------|
E|---------------------------10------------------------------------|

(The first time through you only hit frets 3, 5, and 9 once.  After that you hit them 
quickly three times and use a four on the D string instead of a 9 on the A,  like this):

e|-----------------------------------------------------------------|
B|-----------------------------------------------------------------|
G|-----------------------------------------------------------------|
D|---------------------4~~~----------------------------------------|
A|--3-3-3-5-5-5-7-7-7----------------------------------------------|
E|-----------------------------------------------------------------|

Guitar II:

e|-----------------------------------------------------------------|
B|-------12-10----10------------------------12-10-----10-----------|
G|--9-9--------12------12-11-12-11-----9-9---------12----12-11-----|
D|---------------------------------12--------------------------12~-|
A|-----------------------------------------------------------------|
E|-----------------------------------------------------------------|

e|----------------------------------------------------5~------------|
B|-------12-10----10--------------------------7-7-8-8---------------|
G|--9-9--------12------12-11-12-11--------9-9-----------------------|
D|---------------------------------12-------------------------------|
A|------------------------------------------------------------------|
E|------------------------------------------------------------------|