I wouldn't do a powerpoint from a paper you've already written, because it might end up being too long and wordy. The way information needs to be presented in a powerpoint is very different from the way it would be presented in a paper, I think.
I do my powerpoint presentations kind of like a sketch, a slide at a time, and fill them in gradually. First, I think about each of the main points I want to make and use that to title my slides and put in the main bullet points. Then I'll fill in any more points or examples I want to add. Then I'll read the whole thing over in order and try to figure out if someone who didn't already know my topic would think the information was clear. Usually at this point I'll have to find a way to cut a few slides. If it seems OK, I'll add charts and graphs and play with the formatting after that. Then I'll read through it compulsively looking for errors about 4 or 5 times (or until I run out of time). I really ought to practice saying my presentation out loud, and time it, after that, but usually I don't because it feels weird reciting my powerpoint out loud to no one, in a dorm with paper-thin walls. So not the most efficient method ever, I admit, but people seem to understand and like the results well enough, so I guess it works. ::shrug::
Oh yeah, and when you're giving your presentation, be sure to talk slowly and put spaces between words! You seem like you would talk really fast in real life.
Awesome topic, btw. Are you talking about how short term memory and long term memory are different, or their neural basis, or what? Good luck!