Hey guys,
I feel a need to chime in here, and give you a couple of pointers about this great song.

First off the G chord is not really a G chord, it's actually what's called a sus chord. Which is short for suspended chord, to put it another way I would call this a G sus 5 chord because I'm adding another D note to it. This is my way of remembering this, not sure if it's the correct terminology or not.

The best and quickest way to explain this is to tell you how to make the chord.

Index finger 2nd fret 5th string
Middle finger 3rd fret 6th string
Ring finger 3rd fret 2nd string
Pinky 3rd fret 1st string

Strum all the strings for this one, and the next chord is what makes the song in my opinion.

Drop your index finger to the 2nd fret on the 1st string, and pick your pinky up. This will give you the part that hasn't quite matched up, and will look like this.

Index finger 2nd fret 1st string
Middle finger 3rd fret 6th string
Ring finger 3rd fret 2nd string

This is a sus chord also, I would call this a G sus 7 chord because I'm adding an F# note. This is the 7th note of the scale, but not always the 7th of the chord. The F note in the first fret on the first string is used in a G major 7th chord. You're still adding the 7th note, but you can tell a big difference in these 2 chords.

On this 2nd chord, you really want to try to catch the bottom 4 strings. Practice these 2 chord positions, get the switching down, and then try strumming it.

Here is the progression for the intro of the song.

G sus 5, G sus 7, C, Am, D, G sus 5

Work on this, and it should help you figure everything else out. Let us know how it goes, and I hope this helps. Many of my bluegrass lessons use the G sus 5 chord, including this latest tutorial.

http://www.guitartricks.com/tutorial.php?input=995

You may think that bluegrass can't help you, but knowing these strumming patterns will be helpful in many styles of music. Ok, that's it from me, be sure to let us know how you're doing.