Maybe if you put vaseline all up yer fretboard...just kidding, don't do that! Perhaps changing brands or types of strings might help. As for removal of the sound post recording, that's gonna be tough. There's programs (Cakewalk, Acid Pro, etc) that can expand the view of the signal's wavelength, and then edit individual peaks of noise. But I'm with Scott...I've grown to like those kinda nuances, because it's an instant reminder that someone real is playing. Plus it's part of the character of the instrument that say, a piano, doesn't have.