Power Chords

Hi. I've got another question. When I was learning to play guitar, I always played power chords using my first finger and have the pinkey bar across the two lower notes. For example to play an "A" Power Chord I would put my index finger on the fith fret E string, and then have my pinkey bar across 7th fret A and D string. I've been looking at tutorials for powerchords for the heck of it and saw in examples people use the 3 & 4 fingers on the two lower strings rather than just use the pinkey to bar across both.
Maybe this is just a stupid question, but is there any disadvantage using the technique I use? I've been playing guitar like this for like 1-2 years now and to start over trying to learn to play a darn powerchord would suck... but I would do it. I'm actually teaching myself to do the powerchord the "right" way now. But all my dexterity and accuracy is gone when I use this method.

If one day you want to play something that includes power chords and little single notes riffs, you might want to learn both ways. But from the videos of metallica I have seen, well... Hetfield does it your way, and it doesn't bother his playing it seems...

The thing with playing guitar is there is no one "correct" way of playing (aside of saftey factors where you might actually damage your muscles) If it's comfortable and works for you, then there's no really problem with it.
The only disadvantage your method has is if you wanted to pick a note higher as part of the riff. If your third finger was being used your pinky would be free to play the higher note......
That doesn't actually make a lot of sense, but hopefully you followed it.
I used to play the with that method until I realised it was more beneficial to my barre-chord to play the barre with my third finger, (for the reason I gave above, your pinky is "free" to play something else)
Now my dexterity is good enough that I can play power chords with several different fingers if I need to. I think the important thing is to not try and limit yourself to one method - if you can play it several different ways you'll be ready for almost any situation you might come across.
Hope that's helped, if you've any more questions feel free to ask me or anyone else (someone'll be able to explain it a damn sight better than me). Good luck and "rock on"!