The chords in the verse are Dm and C,
The Chorus is Dm - C - Bb - C

The Dm is played like this, C, and the Bb
e--------------------------------------------------------|
B-15---------------------------------13-----------11-----|
G-14---------------------------------12-----------10-----|
D-15---------------------------------10------------8-----|
A-12---------------------------------10------------8-----|
E--------------------------------------------------------|

If you want to play with multiple people on one guitar, forget about the B string ;)

Giani's intro:

e--------3--3--5-6-8-5-3---1--1--0--0------------|
B--1--1--------------------------------3--3--1---|
G------------------------------------------------|
D------------------------------------------------|
A------------------------------------------------|
E------------------------------------------------|

e--------3--3--5-6-8-5-3----------0--------------|
B--1--1--------------------3--3------3--3--------|
G------------------------------------------------|
D------------------------------------------------|
A------------------------------------------------|
E------------------------------------------------|

Marshall plays exactly the same as Sarah, on the E string, but you guys can figure out 
the rythm :)