paxil has some nasty side effects. I took it once for about six months. It made it pretty hard to "finish" my marital responsibilities.
Talked to the Doc and switched to Zoloft and that side effect stopped right away. Zoloft's only side effect is if you miss a day, you get dizzy easily.
Xanax is the ideal drug for you, works fast (15-30 minutes) and doesn't last more than a couple hours.
However, I used to be deathly afraid of speaking, and I've found that I just had to endure the apprehension for a while, and now it's no big deal. Preparation, rehearsal, having a contingency plan (in case you're using powerpoint) and confidence is the key!