Scott,
when an equalizer lets you set a frequency usually it works like a parametric equalizer and this means that it will boost (or decrease) the chosen frequency and other frequencies around that one in a "bell shaped" way. In other words, the chosen frequency is the center of a bell shaped curve; in a true parametric equalizer you would be able to determine the width of the curve, but in this case I think that the width is predetermined and rather narrow, to prevent the equalization to interfere with unwanted frequencies.
I hope that what I am saying doesn't sound too confusing.
Enjoy your PSR 2000
Andrea