You've gotten a lot of good advice here and I sincerely hope it helps you. I'm in a similar situation and must give the "final presentation" for a class tomorrow morning. So this topic of public speaking has been much on my mind of late. Please allow me to share what I've learned and build upon the valuable advice others have already given.
Be Prepared! This is possibly the best advice there is. You have to know your material inside and out, backwards and forwards. Not only will this give you more self-confidence it will also help when you need to juggle your thoughts while you're speaking. There are a number of ways to do this and here's what works for me.
I organize my thoughts into a logical progression from one topic to the next. Then I actually type out a rough draft of my speech and begin memorizing what I want to say about each topic. I don't think you should necessarily try to memorize your speech word for word but instead memorize all the things you want to say about a particular topic. That way you can assemble them in any order you choose when you're giving your speech. When I give my speech I will probably stray from the original line of thought I first imagined...but when I do I know that my familiarity with the subject matter will make it easy for me to get back on track.
I can't emphasize enough how important preparation is.
Second, you're going to be nervous, accept it, plan for it and move on. I think the vast majority of people have great difficulty with public speaking. So, know that you're not alone...almost everyone that engages in public speaking feels exactly the same way about it as you do. I don't like the idea of alcohol or drugs to help you calm down...I believe you can do just fine with the chemicals already present in your body.
But that's just me.
What I do is to build the nervousness into my speech...I plan to be nervous, I expect to be nervous! But I know that the nervousness will pass and it will pass fairly quickly. At some point in your speech you will relax and be able to deliver the material exactly as you wanted to deliver it. Anticipate that moment and plan for it! I usually give myself a couple paragraphs at the beginning and then by the third paragraph I "expect" to be fine and relaxed again. You'd be surprised how well this works. Then all you need to do is practice those first two paragraphs till you can say them in your sleep! (This goes back to the whole preparation thing)
Third, do you want to give a good presentation or simply survive? If your goal is survival than disregard the following point. If you want to give a good presentation then my advice is to make eye contact!!! Shift your gaze from person to person in the room as you deliver your speech. It looks so much better than burning a hole through the back wall with your eyes. Remember, these people have no idea what you're about to say and if you miss a line or skip a word...you're the only one who will know.
Lastly, just to repeat some excellent tidbits I've read by other posters. Keep your hands out of your pockets. Sew those pockets shut if you have to but don't hide your hands in there! Use your hands to talk, gesture with them. If nothing else grab a pencil and use it to illustrate points the way a conductor communicates with the orchestra through a baton. Hey, it'll get their attention!
Also, (as someone else pointed out) watch your "ums". This, again, goes back to preparation. You want to be familiar enough with your material that it's on the tip of your tongue. Stalling for time with something like "um" just looks bad. Also watch other ineffective speech habits such as "like", "ya know" or "whatever".
Ok, last thing and I'll stop. What I do and what works for me is that I practice the first paragraph, reading and then saying it aloud over and over till I can deliver it any way I want to without much effort. I continue to practice it till I no longer need my draft to guide me. Then I start doing the same thing with the second paragraph. BUT, when I practice the second paragraph I also practice the first one on the way to the second. (So I actually practice the first two paragraphs) Then when I'm on paragraph three I run through the first two paragraphs on my way to the third. I know this sounds like a LOT of overkill but the net result is that you learn those first few paragraphs really well...which is exactly what you want to be prepared for the nervousness that will most likely accompany those first few paragraphs.
You can do this. And you can do it well. You've got plenty of time to practice and get prepared to make an excellent speech. Don't give up, you've got everything you need. Now go out there and knock 'em dead, slugger!