I've had my 3GS for something like 4 years now, and I'm gonna upgrade it this year when the next iPhone comes out. Anyway, until then, I could do with cleaning it. There are some specs of dust beneath the screen which is really annoying, and there's a lot of dust in the speakers/microphone which I'm sure is muffling sound. Is there a guide on cleaning this sort of stuff? I've attached a picture for reference of the dust in the speaker/microphone...it doesn't look as bad in the picture than it really is.