My preferred powerpoints support the talk. They provide things the speaker cannot- pictures, tables, graphs. Sometimes bullets are nice for openings and closings to summarize.
I did a presentation recently regarding Git and git-enabled workflows to a room of people with SVN and TFS backgrounds. The only slide I relied on was the git-flow workflow graph. Everything was a live demonstration of the workflow by actually using git live on the screen.
A projector during a presentation should be used to show what you cannot say or to clarify a point graphically.
