I prefer to play this song in the key of A using open chords.

CHORD CHARTS
E     [0 2 2 1 0 0]
Esus  [0 2 2 2 0 0]
C#m   [x 4 6 6 0 0]
B     [x 2 4 4 0 0]
A     [0 0 2 2 0 0]

Intro
E Esus4 E Esus4

Verse
E
Looking out my window
E                 Esus4           E
I see the trees blowing in the breeze
E
Looking out my window
E                Esus4         C#m
I see the birds flying in the sky


Pre-chorus
        B
And I know
       A
With just one breath
                       C#m
You created the whole world
        B
And I know
   A
If I don't praise You
                        C#m      B       A
The rocks will soon cry out,cry out,cry out..


Chorus
E
Praise Him
E
Lift your voices
A
Let it ring
                    E
Throughout all the earth

E
Praise Him
                        A
Let all men know that Jesus Christ
        E
He is alive!