Kevin,
I had similar questions about the beam calculator. It has too many problems right now for me to use it. I don't use it because of all the problems. Try going back and editing your beam calculations. When I do it, the graphical rep of the supports are moved away from the beam and I can't get them back on it. I have to delete everything and start over each time. I am using a "Custom" beam and not one from the Content Center. That may make a difference. The link to my post is
http://discussion.autodesk.com/thread.jspa?threadID=567615. You may find something in it that may help you out. Just be aware that the deflection from beam self weight is included in the deflection calculations.
I ran the numbers for the loading with both Inventor and another beam program that I use. Inventor gave me a deflection of .769in and the other program gave a deflection of .761in.
I have attached my results here for a comparison. I added two additional supports (more like your picture), just to see what would happen. The deflection then dropped to .193in at the center.