I think you'll actually have a difficult time keeping it down to only an hour. As the others have said, the only way to know is to deliver the presentation several times. Start off by delivering it to an imaginary group of people in the comfort of your own home just as if it were a real group. Then present it at your local PASS chapter meeting or to a remote user group as has already been suggested. They'll be happy to have one of their own presenting. After you get the kinks and the butterfly's out, you do very well at an SQL Saturday or other public event.