One thing that may help you a bit more is to put in a keyframe rate. A keyframe is basically a refresh on the entire screen in the movie that makes everything look very sharp. So, if you have a lot of motion in your movie, you might want to have a keyframe every 5-10 frames (assuming your framerate is 30 fps). If there's not as much motion, a keyframe every 15-20 frames might work better.
The reason you need keyframes is because when you compress a movie, no matter what kind of codec you use, there are going to be a lot of artifacts from the compression (blurry video, large squares of blurry color, etc.). Keyframing is the solution to this. if you have it put in a keyframe every five frames, then Quicktime will put in a high quality image every five frames for the compression to work off of. This way, there is not a lot of room between keyframes to muck everything up.

It's really hard to explain, but I hope you caught the gist of it.
If file size is not an issue for this "full screen presentation," then I would go with having a keyframe every 3-5 frames, even if there's not too much motion. This will ensure that your movie stays crisp.
Now, if you walk away with only one thing from this explanation I've laid out for you, walk away with this:
Lower number in "Keyframe every (____) frames" box = sharper video quality.