I don't have enough patience to tab it perfectly, but all the notes are correct. Just 
to the song and you'll know when to use each riff.

Ok?

So, lets get started:
I think Angus uses a slide to play this song, but a might be wrong...

x/y -> slide from x to y
~ -> hold note for a bit
* -> mute strings

ANGUS:
Intro
e|-------3-------1-------0------1--0--1--0--|
B|-----3-------3-------3------3--3--3--3----|
G|---0-------0-------0------0--0--0--0------|
D|------------------------------------------|
A|------------------------------------------|
E|------------------------------------------|


Basic Riff
e|--------------------------------|--------------------------------------|
B|--------------------------------|--------------------------------------|
G|--0-3-0-3-0-3-0-3/5~--3-0-3/0~--|--3/2-0-3/2-0-3/2-3/5~--3-0-3*3*3-0~--|
D|--0-3-0-3-0-3-0-3/5~--3-0-3/0~--|--3/2-0-3/2-0-3/2-3/5~--3-0-3*3*3-0~--|
A|--------------------------------|--------------------------------------|
E|--------------------------------|--------------------------------------|

Chorus Riff
e|------------------|--------------------|
B|------------------|--------------------|
G|---10/5~--3/12~---|---10/5~--15*-12~---|
D|---10/5~--3/12~---|---10/5~--15*-12~---|
A|------------------|--------------------|
E|------------------|--------------------|

MALCOLM

Intro
e|--3------------|
B|--3------------|
G|--0--5--3--0---|
D|--0--5--3--0---|
A|-----3--1--x---|
E|-----------3---|

Everything else (just change a bit the rhythm for the last note some times)
e|---------------|
B|---------------|
G|--5--5--3--0---|
D|--3--5--3--0---|
A|-----3--1--x---|
E|-----------3---|


This is it...

Yep, its simple.

There are some notes Angus plays that area bit hard to listen clearly. But nothing 
hard to tab. I'm just lazy.