Given the fact that you have to give this speech, presumably for a class, I would make sure you check to see if there are any requirements that you have to include. That has to guide your work more than anything else. In terms of your speech about Buddhism, I think you have to find something in the religion that is interesting to you. Since this speech is five minutes, it's going to be ineffective if you are not able to "sell" it to your audience, and I think that being able to identify elements of the religion that you find interesting will help you "close the deal" to your audience. I think that one element that would be interesting to discuss would be how the religion addresses the issue of suffering. For Buddhists, this is one of the central issues of being in the world because it was of intense importance to the Lord Buddha, himself. It might be interesting for you to give an overview of how the Buddhist sees suffering and then how they address the issue of suffering in their own lives and in accordance to their religious values. Along these lines comes the issue of compassion and how one embodies this in the face of intense pain and suffering in the world. Additionally, it might be interesting to examine the political implications of Buddhism with the case of the Dalai Lama, the spiritual leader of Tibet and Buddhists all over the world who was exiled from his home by the Chinese. This might be a topic to examine in your speech that will be able to hold the audience and you, if you are able to find interest in it.