Wow, old thread, but while doing a search for 'effects' this one came up (nervousness effects people in very different amounts).
Just wanted to add that my wife is a psychologist and she says there are medications available for performance anxiety that are very mild (won't effect your performance in a negative way like alcohol) if you are severely plagued by nervousness.
I've found that confidence and preparation are the keys to overcoming nervousness. Preparation from knowing your material so well that you could play it in your sleep let's you focus your attention on dealing with other random things that WILL occur like equipment failures (broken strings, bad cables/unplugged, out of tune, no monitors, etc.). Confidence will follow with experience, and is an emotion that is self induced (just like fear). Fill yourself with confidence instead of fear and you won't have to picture the audience naked, because the girls will sense it and get naked for you by throwing thier clothes onstage! hehe.
If that fails, I will have 1 or 2 beers to relax myself right before going on. Don't overdo it.