Aww thanks buddy. For all y'all who are curious, here is BGD's "when to play a power chord" top 5 list:
1. Are you playing hard rock or metal? If yes, play a power chord.
2. Are you familiar with the chord?
    If Yes: Play the chord as written, lazy! 
    If No: does the chord have a "b5" or "aug" in it? If "no," play a power chord. If "yes," grab a beer and wink at the blonde in the front row.
3. Is the other guitar player wildly out of tune? If yes, play a power chord.
4. Do you want to hit a chord Townsend windmill style? If yes, play a power chord.

and finally....

5. Are you still having problems with that dang "B" chord? If yes, play a power chord.

That's some funny s*** right there.  True, nonetheless.  Which is why it's funny!

Thin instrumentation also calls for bigger chords. I can get away with lots of power chords in a 5 piece, but the three piece I'm in requires greater density.

Aww thanks buddy. For all y'all who are curious, here is BGD's "when to play a power chord" top 5 list:
1. Are you playing hard rock or metal? If yes, play a power chord.
2. Are you familiar with the chord?
    If Yes: Play the chord as written, lazy! 
    If No: does the chord have a "b5" or "aug" in it? If "no," play a power chord. If "yes," grab a beer and wink at the blonde in the front row.
3. Is the other guitar player wildly out of tune? If yes, play a power chord.
4. Do you want to hit a chord Townsend windmill style? If yes, play a power chord.

and finally....

5. Are you still having problems with that dang "B" chord? If yes, play a power chord.

I would say #6  If your song is the same 3 chords, intermix open and power. adds dimension.

and finally....

5. Are you still having problems with that dang "B" chord? If yes, play a power chord.

For specific help, I recommend checking out the theory section of the forum:

http://www.chordie.com/forum/viewforum.php?id=21

Or, as I like to think of it, the "Russell-Jerome-Baldguitardude school of Music Theory".  99% of what I know I learned from those guys.

christopaul wrote:

Is that the same as A sus ?

Not quite.

As per above, "no3" means play a power chord (1 and 5 only).

"sus" means to SUSpend the 3 in favor of the 2 (for sus2) or the 4 (for sus4).

Basic chord structures:

Major triad:  1-3-5
Power chord (aka no3):  1-5
sus2:  1-2-5
sus4 (aka "sus"):  1-4-5
Minor triad:  1-b3-5

And for explaination of power chord, its not the 1st and 5th frets, its the notes. AKA a root 5th.  your 1 (being the root note and also played with your index finger) and your 5th (Usually played with 3rd or 4th finger)  an A power chord in the 1st position is
http://www.cyberfret.com/wp-content/upl … string.gif
AND THE COMMON 5TH FRET POSITION
http://purpletigerguitar.com/wp-content … 02/A51.jpg  This pic shows the index on the low e fret 5 and the 3rd finger on fret 7 on the A string. also the pinky on d string 7th fret. you do not have to use the pinky but it makes for a heavier sound.
but that is the jist of it and about all the theory I can handel LOLOLOL

Is that the same as A sus ?

Not quite.

As per above, "no3" means play a power chord (1 and 5 only).

"sus" means to SUSpend the 3 in favor of the 2 (for sus2) or the 4 (for sus4).

Basic chord structures:

Major triad:  1-3-5
Power chord (aka no3):  1-5
sus2:  1-2-5
sus4 (aka "sus"):  1-4-5
Minor triad:  1-b3-5

Beamer, Roger and Russell are correct.  "no3" means play the chord without the 3rd.  Play the 1 and 5 only.

In other words, it's a power chord.

I know this to be true because I had to research it for myself.  When I first saw it, I thought "A no 3" meant "A chord number 3".  And I thought, "wow, so different variations of chords are designated by numbers?"  So then I went off to look for the fingering for A number 3.  Needless to say I didn't find it. 

HOLY COW! I WAS CORRECT! I just didnt realize it was also a power chord! LOLOL love it.  glad I could help a bit (for once on theory)

In other words, it's a power chord.

I know this to be true because I had to research it for myself.  When I first saw it, I thought "A no 3" meant "A chord number 3".  And I thought, "wow, so different variations of chords are designated by numbers?"  So then I went off to look for the fingering for A number 3.  Needless to say I didn't find it.