I've been asked to do a one hour presentation on Security threats and tools. I know, one hour isn't much but I was thinking along the lines of presenting on the most common tools used in Hacking/Cracking.
I think you need to ask and think about a few questions first.
Get with the organizers, and find out how much time you have to do the presentation. Are you one of multiple people doing presentations that day? Does your one hour include the time you have to set up your equipment and break it down, or will you have extra time.
Find out what the organizers' expectations for your presentation. You might be thinking of showing them lots of cool things, while they're thinking how to help users defend themselves.
Next, think about your audience. Who are they, and why are you there? Then think about what you'd like to see if you were in their place.
Based on what you think they'd like to see, and what the people who contacted you want, build your plan off of that.
Also remember, there will always be questions, give time for them to ask, and be able to expand from that point.
Don't know if you've already done that part, you didn't say from the original post.
Look forward to hearing more about your Presentation.