Ahhhh, performance anxiety; this is something I know too well. When I find myself in such a position it is helpful to remind myself that I am not alone. Think of the fact that most others at this conference are going to be anxious as well. I think of the fact that countless people go through this and come out the other side no worse for wear - and you are likely more on the ball than the majority of them. If they were able to do it, so can you.