We work with a printing company and have a special plot style table that we use with them. When I plot the drawing, and then view it with Buzzsaw Apprentice, I can see when the pen styles are correct because they are listed on the left toolbar. These two workstations appear to produce different pen styles, for some reason, even though I have them set up the same as far as I know how.

Both workstations are using the full version of AutoCAD Architectual Desktop 2007, and use the same plot style table (shared on a file server), and am testing them with the same drawing (also shared on a file server). I have exported the user settings from one workstation, imported it on the other, and set as current, to no avail.

As a novice with AutoCAD, what could I be missing?

They should both be the same provided you are using the same plotter.  Some plotters act diffrent so even though your using the same pen style it will look diffrent depending on the plotter.  the same is true on PDF software as well.  Make sure you use the same plotter/PDF maker on both machines.  that should fix your problem.  I hope this helps.