It's played in open D tuning with a slide but even if you don't want to re-tune your 
guitar, you can still play in regular tuning without a slide! :)

If you're not going to re-tune play it with power chords (open chords sound bad) and 
ignore the slides and tabbed bits:) I'll be tabbing out the whole thing with accuracy later!

If you're going to re-tune and play with a slide:

Okay, so first things first you have to re-tune your guitar to open D which is
E down to D
a same as a
d same as d
g semi-tone down to f#
b down to a
e down to d

When you strum your guitar open you should have a D chord! Note: It's pretty much all 
arpeggios but you can strum it!

The high pitched beggining part is tabbed

(6th string) d--13/15--13--13/15- x4

(2nd)a----0/5--5--5/7--|
(3rd)d----0/5--5--5/7--|
(4th)f#---0/5--5--5/7--|



D (open)
First time I saw her she was standing in line,

D (open)
Holding a book about compatible signs,

G (slide up to your 5th fret)
I should have talked to her, I should have tried,

A (slide to 7th fret)
But I was breathless by the look in her eyes,

Then gentely slide back open

You repeat the same thing through all the verses AND chorus's

D (xx0232@1)                    DIf (xx0232@1)you see Kate tell her that i'm looking for her,

G (slide up to 5th fret)
She's so fine,

A (slide up to 7th fret)
That girl's been on my mind,

etc.

The only time it changes is when he does the weird bridge thing at the end, it changes to

B (x2444x@1) A (x02220@1)  G (320003@1)         finish with an open D (xx0232@1)She's been on my mind ..

It really is quite simple :)