in school i hated presentations- now i love them... we don't have many of them- maybe 2-3 smaller ones per semester but i normally feel comfortable. though i think that jimbo is a smartass, his points were really good. imho the most important thing is that you know what you're talking about. get into the material as deep as you can and it's always necessary to know your stuff better than the audience does- know more than you actually say! this makes you feel comfortable at what you're doing and it takes away the fear from the questions.
it's normally no problem to lose control for a small amount of time. the guys listening to you know that everyone everywhere makes mistakes and it's not the problem that you make mistakes- the problem is how you handle them! in these situations you see who's professional (he probably makes a little joke and gets back to the beaten track without losing his souvereignity) and who's not (tapping around from one feet to another in accelerating speed, getting a tomato face, starting to shake with hands, libs, eyes...) in such cases body language is most important.
at presentations you don't present a subject- you present yourself. if you speak and gesture confidently you can tell the guys all the shit you want and they will belief but if you behave like a neurasthenic nerval wreck nobody will belief you even the hardest facts.