quite simply, heres the bass riff

G -----------------------|
D ----------3-55555555---|
A -55555555--------------|
E -----------------------|

chorus

G -----------------------------------------------------------------|
D -33-33-55-55-33-33-55-55-33-33-55-55-33-33-55-55-5-5-5-5-5-5-5-5-| etc
A -----------------------------------------------------------------|
E -----------------------------------------------------------------|

of course you can play the D or G string open at the right places if you wish, but i use 
way just for entertainment reasons.
feel free to correct and modify this, cheers